Nadal, who hasn’t hit a ball in anger since pulling out of the Australian Open quarter-finals in January, saw Federer take over top spot on February 18.
The Swiss veteran, however, slipped 10 points behind his Spanish rival and into second place after a second round defeat to Kokkinakis that saw the towering American leap eight places to ninth thanks to his eventual victory Sunday in the Masters 1000 event.
Isner thus equals his previous best ranking of ninth, reached in April 2012, while beaten finalist Alexander Zverev of Germany moved up one place to fourth.
South Korea’s Hyeon Chung meanwhile continued to chip away at the rankings, the 21-year-old breaking into the top 20, to 19th, for the first time in his fledgling career thanks to his quarter-final appearance in Miami.
ATP rankings at April 2(change in ranking in brackets):
1. Rafael Nadal (ESP) 8.770 pts (+1)
2. Roger Federer (SUI) 8.670 (-1)
3. Marin Cilic (CRO) 4.985
4. Alexander Zverev (GER) 4.925 (+1)
5. Grigor Dimitrov (BUL) 4.635 (-1)
6. Juan Martin Del Potro (ARG) 4.470
7. Dominic Thiem (AUT) 3.665
8. Kevin Anderson (RSA) 3.390
9. John Isner (USA) 3.125 (+8)
10. David Goffin (BEL) 3.110 (-1)
11. Lucas Pouille (FRA) 2.410 (-1)
12. Pablo Carreno (ESP) 2.395 (+7)
13. Novak Djokovic (SRB) 2.310 (-1)
14. Sam Querrey (USA) 2.265
15. Diego Schwartzman (ARG) 2.220 (+1)
16. Jack Sock (USA) 2.200 (-5)
17. Roberto Bautista (ESP) 2.175 (-2)
18. Tomas Berdych (CZE) 2.140 (-5)
19. Hyeon Chung (KOR) 1.897 (+4)
20. Fabio Fognini (ITA) 1.840 (-2)
Rafael Nadal has withdrawn from the Mexico Open after suffering pain in the area of a hip injury that forced him to pull out of the Australian Open last month.
The Spanish top seed and 16-time grand slam winner was due to face countryman Feliciano Lopez in the tournament’s opening round in Acapulco.
Announcing the “sad news” on Facebook, he said that during training he had felt pain in the area where he had suffered the injury in Melbourne.
He added: “This morning we went to the hospital and did an MRI. We’ll have to do more tests to see the extent of the injury.
“For now the sad news is I will not be able to play here in Mexico before this wonderful audience who always treats me with so much affection.”
In January, Nadal suffered an injury to his inner right hip muscle during his quarter-final clash with Marin Cilic and was forced to withdraw two games into the final set.
But the Spanish star said Saturday he feels good and his motivation remains strong.
Nadal, who is gunning for a 17th major title but only his second Australian Open crown, was hampered by a knee injury at the tail-end of the 2017 season.
It forced him to skip the lead-up Brisbane International this month, and he has only had a one-match workout at the exhibition Kooyong Classic in Melbourne ahead of the Grand Slam starting Monday.
Yet he is unfazed and raring to go as seeks to go one better than last year when he lost an epic Melbourne Park final to Roger Federer.
“Is the first time I am here without playing an official match in my career. It’s a new situation for me. But I feel good,” said the 31-year-old, who played his first Australian Open in 2004.
“I feel that I had a good week-and-a-half of practices. I really hope to be ready. I feel myself more or less playing well.”
With so few matches under his belt ahead of the season-opening Grand Slam, he asked organisers if they could do him a special favour, and they obliged.
It saw Nadal play Austrian world number five Dominic Thiem this week on a practice court under full match conditions, with ball kids, scoreboard, and umpire.
— Hombre Nadal (@Rafa_Minato99) January 12, 2018
“I wanted to play a couple of close competition matches. I played in Kooyong once. The club in Kooyong is great, but at the same time the conditions of play are completely different from here,” he explained.
“That’s my feeling. We decided to play another match. Talking with the Australian Open, yeah, they gave us the chance to play like an open practice but closer to the match for the crowd.
“We did it. It was a good practice, good feelings for both of us I think. The job was done the right way.”
HEALTHY AND COMPETITIVE
Despite his achievements in a long career, motivation for Nadal, who needs to reach the quarter-finals to be certain of retaining his world number one ranking, with Federer breathing down his neck, remains undiminished.
— Rafa Nadal (@RafaelNadal) January 13, 2018
Not only can he clinch a 17th Grand Slam in Melbourne, but he also has the opportunity to join Roy Emerson and Rod Laver as only the third man in the Open era to win each of the four Grand Slams twice.
The only place he is yet to achieve the double is Australia.
“For me, the Australian Open always, if you are not 100 percent motivated to play this tournament, you probably you don’t love this sport,” he said.
But he knows anything can happen so early in the season, despite being the top ranked player in the world.
“Everyone starts from zero. I start from zero again,” he said.
“It’s the start of a new season, an exciting one. I hope to be healthy and competitive, and most important thing, I hope to enjoy tennis one more year.”
In Melbourne, Nadal is at his first major tournament in years without his uncle Toni, who coached him from childhood until after his US Open win last year.
Toni Nadal is now coaching at the Rafael Nadal Academy, with his nephew under the tutelage of Carlos Moya.
“In terms of professional things, I spoke to him few days ago, speaking about how the life going, how the tennis going,” he said of Toni.
“If I have something to ask, I ask him. If he have something to tell me, he call me and tell me.”