The pair both missed last weekend’s Community Shield victory over Chelsea at Wembley after enjoying delayed summer breaks following the World Cup.
De Bruyne and Sterling, who reached the semi-finals in Russia with Belgium and England respectively, returned to training on Monday and have quickly got back up to speed.
“They are available,” said Guardiola at his pre-match press conference. “Raheem and Kevin arrived quite well.
“Three weeks off is not too much time after the World Cup and both arrived in the perfect way.
“Sterling was fit in four or five days. He’s not a big guy who needs training, he’s sharp so it’s easy.
“Kevin arrived in the perfect way. He’s going to be a father for the second time. He must look after his wife – that’s why he came back in a perfect way.”
Guardiola confirmed that City failed in their bid to obtain a work permit for Brazilian midfielder Douglas Luiz this week.
The 20-year-old, a £10million signing in 2017, was loaned out to Girona last season and is now likely to be sent out again for the coming season.
Guardiola had hoped to bolster his midfield options with Luiz after failing in an attempt to sign Jorginho, who opted to join Chelsea from Napoli.
City did not get endorsement from the football Association for their work permit application and Guardiola was unhappy with the decision.
Guardiola said: “He’s not allowed. We are going to try to help him to go on loan again and try to get the work permit.
“It’s so difficult for me to understand. One guy who doesn’t see the player or any training sessions every day has to judge if (Douglas) has the ability and quality to play.
“I accept the rules but I don’t understand. I am so sad and disappointed for Douglas because he could help us.”
Guardiola hinted the club may have tried harder to sign additional players before Thursday’s transfer deadline had the decision been communicated earlier.
He said: “I would have preferred it if it wasn’t announced yesterday. If they decide the rules are the rules, let me know 15 days ago and maybe we can decide what we can do.”
Guardiola said he did not know on what criteria the application had failed.
He said: “I don’t know – not tall enough, doesn’t play enough, games in the past or something like that.”
One of the more unlikely stories of the summer saw Guardiola linked with the managerial vacancy for the Argentina national side.
Argentinian football Association president Claudio Tapia claimed an approach was made to Guardiola but the City boss was too expensive.
Guardiola said: “I’m a little bit disappointed because he cannot say (that). To know that he has to know my salary.
“Nobody contacted me because of course I have a contract and I want to stay here with this project until the end. It was not correct to say the reason why.”
He added: “The Argentina national team has to have an Argentinian manager.”
Sarri, speaking ahead of Saturday’s Premier League opener at Huddersfield, said: “I think it’s impossible. Here the market is closed, so we cannot change important players now. It’s impossible.”
Goalkeeper Thibaut Courtois left Chelsea for Real Madrid this week, urging his Belgium team-mate Hazard to join him in future.
“Hazard is with us,” Sarri said.
“I think definitely. It’s not a problem. I have spoken with him three, four times, for everything. He never said something about the market. I think he’s very happy to stay here.”
Hazard’s contract runs until June 2020 and he has been mulling over the offer of an extension for some time. Sarri believes Hazard will commit to the club.
Sarri added: “I don’t want to discuss about contracts. It’s not my job. My job is on the pitch. My job is to improve the players. My job is to try to win matches.
“It’s not to sign new contracts. I have seen a player very happy to stay here. So I think it will not be a problem, the new contract.”
Sarri suggested there will be departures before the end of the month, with the likes of Belgium striker Michy Batshuayi and France midfielder Tiemoue Bakayoko linked with loan moves.
“Now I think the squad is too large. So I think some players have to go on loan. I don’t know who at the moment. I prefer to have 23, 24 players and three, four, very young players. No more.”
Sarri refused to criticise Courtois for his failure to attend Chelsea training, kissing the Real badge at his unveiling and encouraging Hazard to move.
Mateo Kovacic moved from Real to Chelsea on a season-long loan and Kepa Arrizabalaga has succeeded Courtois as Chelsea’s number one, becoming the world’s most expensive goalkeeper in a £72.1million deal from Athletic Bilbao.
“I’m very happy for both,” Sarri added.
“The Courtois situation was clear. He wanted to go to Madrid, so we lost maybe one of the most important goalkeepers in the world now.
“We bought a young goalkeeper, I think one of the most important amongst the young goalkeepers in Europe. I’m really happy.
“I’m really happy with Kovacic. He has the characteristics for us. I’m really very happy and I think now the squad is complete.”
Asked if Kepa can be better than Courtois, Sarri said: “Not at the moment, for sure. He’s very young, 23.
Sarri on Kepa: "I am very happy for both, because Courtois's situation was clear. He wanted to go to Madrid. So we lost maybe one of the most important goalkeepers in the world, but we bought a young goalkeeper, one of the most important among the young one in Europe" #CFC— Nizaar Kinsella (@NizaarKinsella) August 10, 2018
“I hope he can improve very fast. For the moment he’s not Courtois, for sure.
“Kovacic is a very technical player. He’s able to play between the lines of the opponent. For us it could be very important.”
Sarri did not confirm if Kepa will start at Huddersfield, so Willy Caballero could continue in goal. Cesar Azpilicueta will captain the side.
With no option to buy included in the loan agreement, the Croatian will likely stay in London for just one season. Kovacic is hoping to establish his credentials as a starting-quality midfielder for Madrid, which means he’ll have to impress during his time with the Blues.
If all goes well, the 24-year-old could prove to be one of the better loan signings in Premier League history.
Here’s a look at five of the best.
Carlos Tevez, West Ham to Manchester United (2007 to 2009)
After saving West Ham from relegation by scoring in the final game of the 2006/07 season against Manchester United at Old Trafford, Tevez joined his opponents on the day that summer in what was actually a two-year loan signing.
That two-season spell saw United win the Premier League twice, and reach the Champions League final both seasons, winning in 2008.
The Argentine scored 34 goals across all competitions, forming a lethal partnership with Wayne Rooney.
United decided against buying him outright at the end of his loan spell, and he made a controversial crosstown move to Manchester City, where he would win the league for a third time in 2012.
George Weah, AC Milan to Chelsea (2000)
Weah was past his prime by the time he joined Chelsea, at the age of 33, but he still made an instant impact in England after arriving in the second half of the 1999/2000 season.
Just by virtue of his reputation, his signing created a buzz, and though he only scored five goals for the Blues, they were all vital contributions.
He scored a goal apiece in FA Cup ties against Leicester City and Gillingham, firing Chelsea to the final, where they would go on to lift the trophy.
Weah then moved to Manchester City, where he was unable to scale the same heights of his earlier career, but he’ll be remembered fondly at Stamford Bridge.
Henrik Larsson, Helsingborgs to Manchester United (2007)
On the face of it, just three goals – one each in the league, FA Cup, and Champions League – seems like a middling spell, at best.
But signing Larsson after he left Barcelona was somewhat of a coup for Manchester United. The Red Devils’ players benefitted from the veteran’s presence, and he was such a natural fit in attack that Sir Alex Ferguson tried to extend his loan when it ended in March.
To this day, the United manager believes the rest of that campaign – which saw a league title, but a disappointing Champions League exit in the semi-finals against AC Milan – would have gone differently had Larsson been convinced to stay, and the Swedish legend has since admitted regretting his decision not to.
Jurgen Klinsmann, Sampdoria to Tottenham (1998)
Klinsmann was already a cult hero at White Hart Lane thanks to his first spell at Tottenham, when he scored 30 goals across competitions in 1994/95.
But what cemented his status as a Spurs icon was his second spell, when he arrived for the second half of the 1997/98 season. Tottenham were in danger of getting relegated when the German striker returned, but Klinsmann made sure there was no chance of that.
Nine goals in 15 outings fired the north Londoners to safety, and made him a darling of the White Hart Lane terraces forever.
Romelu Lukaku, Chelsea to West Brom (2012-13)
Romelu Lukaku had struggled to establish himself after joining Chelsea in 2011, but the next season, the club decided to give him playing time by sending him to West Brom.
The Belgian was an instant hit, scoring 17 times in 35 Premier League games for the Baggies. He was technically Chelsea’s highest league scorer that season, because none of the players who actually turned out for the club managed to top that.
His goals led West Brom to an eighth-place finish, their highest ever in the Premier League, and included a famous hat-trick against current employers Manchester United – in Alex Ferguson’s final game, no less.