The unbeaten tournament leaders will complete their first clean sweep since 2012 if they can beat Ireland in Cardiff next Saturday, but they had to ride their luck in Edinburgh as Scotland mounted a second-half fightback.
Tries from Josh Adams and centre Jonathan Davies helped Wales to a 15-6 half-time lead but the wheels threatened to come off after the break.
Darcy Graham’s score set up a blockbuster finish but Wales hung on for an 18-11 victory that leaves Gatland on the verge of becoming the first coach to win three Grand Slams.
But the Kiwi confessed his side were guilty of eyeing up their decisive showdown with Ireland during the second half against Scotland.
🏴 18-11 🏴— Welsh Rugby Union 🏉 (@WelshRugbyUnion) 9 March 2019
As expected, a huge battle against an impressive @Scotlandteam - but Wales show strength and resolve to make it four from four in 2019 @SixNationsRugby.
Cymeriad rhyfeddol, perfformaid egnïol. Ymlaen i Gaerdydd gyda'r tîm uchelgeisiol Cymru. #HWFN #ForTheJersey pic.twitter.com/rYq3tUpoPb
“We were pretty comfortable during the first half but in fairness Scotland came out and put us under a lot of pressure in the second,” said Gatland.
“We’ve lost the second half 5-3 but we’ve shown some real character. There were a couple of moments towards the end when Scotland were attacking but we drove them back.
“Any team that’s won a Grand Slam – and I think back even to last year with Ireland and that Johnny Sexton drop goal – you look back at certain games and know you’ve had a little bit of luck.
“Maybe from a coaching perspective we needed to be a bit tougher at half-time. We talked at the break about being pretty comfortable and going out to deliver a second-half (performance). As a result, maybe we were thinking about next week and that Irish game.”
The build-up to the clash was dominated by domestic rugby politics in Wales, with a proposed merger between Scarlets and Ospreys being taken off the table.
Gatland admitted the debate had affected his team but praised them for shaking off the uncertainty to claim victory.
He said: “This is a fantastic group of men that are pretty tight. There’s no doubt this week has had an impact on the players.
“In fairness to them, after the early part of the week they have got on with the job. There’s obviously a lot of emotion involved with everybody, so I take my hat off to them for digging deep.
“We’ve spoken about forgetting how to lose and these guys are finding ways to win. I’m not sure in the past we’d have had the mental strength to keep Scotland out but these guys are finding ways to do that and that’s what good teams do.”
Scotland have now lost three successive games and face the daunting prospect of a trip to Twickenham next week to finish off their campaign.
Injuries to Tommy Seymour, Blair Kinghorn and Graham rubbed salt into their wounds and coach Gregor Townsend admitted he is still unsure whether star full-back Stuart Hogg will be back in time from a shoulder injury.
But his main frustration was the performance of French referee Pascal Gauzere, with Townsend questioning why he did not issue the visitors with a yellow card despite seeing them concede five penalties within their own 22.
He said: “We would obviously have liked to have won that game. We had errors – probably caused by the defence’s pressure. But we had chances.
“There were five penalties in the 22, and to not get anything from that seems like their indiscipline was rewarded and our pressure wasn’t.
“Was I surprised there was no yellow card? Yes. If teams are giving away penalties close to their own try line through cynical play, then you expect that to lead to yellow cards. That is how international rugby is refereed throughout the world.”
Manu Tuilagi led the onslaught as England kept up the pressure on Grand Slam-chasing Wales by overwhelming Italy 57-14 at Twickenham.
Tries by Jamie George, Jonny May, Tuilagi and Brad Shields sealed the bonus point in the 32nd minute to break Ireland’s Six Nations record for the fastest produced by three minutes.
Tuilagi was a marauding presence until his exit in the final quarter and it was fitting that he followed up his first Test try for five years – his last was also against Italy – with a second soon after the interval.
Predictably enough, Conor O’Shea’s men were overpowered with Tuilagi supported by the equally devastating Joe Cokanasiga, who set off like a freight train, faded and then finished explosively.
George Kruis, Dan Robson and Shields added final-quarter tries and it was a bulldozing run from man of the match Cokanasiga that enabled the replacement scrum-half to cross.
It was not until the 62nd minute that Eddie Jones decided to field Robson and George Ford and given the result was effectively sealed around the half-hour mark, it once again highlighted the reliance on Owen Farrell and Ben Youngs.
For England to now clinch the Six Nations title Wales must fall to Ireland in the final round next Saturday and Scotland must be swept aside in a bonus-point win at Twickenham.
They are well placed to capitalise on an upset at the Principality Stadium, while at the opposite end of the table Italy are playing to avoid the wooden spoon.
Aside from their resilience and occasional spells of effective rugby, there was little for them to salvage from their visit to London and the calls for a play-off for Six Nations relegation to be introduced will only grow louder.
Josh Adams has hailed the Wales players’ professionalism as they prepare to continue their Six Nations title and Grand Slam quest against a backdrop of political turmoil.
Worcester wing Adams’ late try sealed victory for Wales over England a fortnight ago.
And the unbeaten Six Nations leaders now face Scotland at Murrayfield, where a fourth successive win in this season’s tournament would leave them chasing silverware against Ireland in Cardiff on Saturday week.
But while Wales look to capture European rugby’s biggest prize, off the field it is a story of domestic strife as debate rages about so-called ‘Project Reset’ and how Wales’ professional regional game will look from next season.
Talks now appear to be deadlocked, a proposed Scarlets-Ospreys merger is off the table and considerable uncertainty remains.
But despite potential distractions, Adams has no doubt that Wales are concentrated totally on their Murrayfield mission.
“We know the importance of this game, and we have to back up the performance against England,” he said. “We are ready to go.
“The boys have taken it in their stride. Every time we have gone on to the training field the focus has been on the rugby.
“All the boys have been really professional in how they have dealt with the situation. The focus is all on Saturday.
“All the goings-on off the field might add fuel to the fire.
“Everything we have done in training has been as normal, and the focus has been there, which has been really good with the distractions elsewhere.
“Everybody is feeling confident. We are just looking forward to getting out there, and come 2.15pm on Saturday, we will let it rip.”
Adams has been one of Wales’ success stories during a 12-Test unbeaten run that stretches back to February last year.
He scored tries in Wales’ last two Six Nations games, and is rapidly emerging as a player who could shine in the high-octane atmosphere of a World Cup later this year.
“I am feeling good at the minute,” the 23-year-old added. “I am looking forward to taking another opportunity and putting my best foot forward again.
“Time in the jersey does help. You learn with each Test match you play.
“The majority of the guys involved in the autumn Tests have come through into the Six Nations. Togetherness is really good.
Alun Wyn Jones offers his thoughts on tomorrow's big @SixNationsRugby clash with Scotland 🏴 Mae'r capten am weld Cymru'n adeiladu ar eu perfformiadau hyd yn hyn yn y gystadleuaeth. #HWFN pic.twitter.com/bZ4iSMSX0G— Welsh Rugby Union 🏉 (@WelshRugbyUnion) 8 March 2019
“All the boys get on well, and that reflects on how we play. We all work really hard for each other. If someone makes a mistake, the guy next to you is working hard to fix it.”
Although Wales have beaten Scotland 11 times from the last 12 attempts, including four out of five in Edinburgh, memories remain from Murrayfield two years ago.
On that occasion, Wales let slip a 13-9 interval advantage and conceded 20 unanswered second-half points as they crashed to an emphatic defeat.
“The boys are still hurting a little bit from that,” Adams said. “They did not perform to the best of their ability, and that was the most frustrating thing.
“If you are a per cent or two off, teams will punish you. It is a little bit of revenge for two years ago, and I am sure the boys who were there that day will want to make amends.