The German, who was runner-up to Serena Williams two years ago, triumphed 6-3 6-3 on Centre Court and is now one win away from a third grand slam title.
This semi-final was billed as attack versus defence and it was the solid, reliable manner of Kerber that prevailed as she let an erratic Ostapenko, who was going for winners almost every shot, hand her a swathe of free points.
Ostapenko won the French Open in 2017 by playing in this manner and knows no other way, but she had an off day and, despite hitting 30 winners, it was her 35 unforced errors which cost her any chance of progressing.
Kerber, who spent 34 weeks at world number one between 2016 and 2017, could be set for a rematch with Williams if the eight-time champion can get past Julia Goerges in the second semi-final.
“This fifth set is one of the best sets of tennis I’ve ever seen live,” said Andy Murray in the BBC commentating booth on Wimbledon Centre Court as he watched Rafael Nadal and Juan Martin del Potro push each other to their limits in the quarter-finals on Wednesday.
Few would disagree with Murray’s assessment. In a 4hr 48min tug of war, Nadal overcame Del Potro 7-5, 6-7 (7), 4-6, 6-4, 6-4 to reach his first Wimbledon semi-final since 2011.
It was such a tense affair, particularly the 71-minute deciding set, that when it was all over, Del Potro lay on the ground, face down, and only got up when he saw Nadal standing over him. The Spaniard had walked over the net to console Del Potro. They hugged, and walked towards the umpire’s chair together, their arms around each other.
“After almost five hours match, I fell down. I wanted to stay there for all night long. But Rafa came to me and we made a big hug, and it was kind of him,” said Del Potro.
Nadal had three set points to go up two-sets-to-love earlier in the match. Del Potro saved the first two on his own serve. But when Nadal had a third opportunity to close out the set, the first on his serve, he double-faulted. Suddenly it was 6-6 at the change-of-ends. The Mallorcan lost the tiebreak 9-7 moments later. He had just lost a 71-minute second-set during which he felt he was the better player.
“Of course I was worried when I lost the second set, no? Winning 6-3 in the tiebreak, it’s true that he played two great points with his serve, but then I make, yeah, very important mistake. That double fault was a big mistake. That’s how it is. Then the match changed,” admits Nadal.
What followed was a battle for the ages. One that is reminiscent of Nadal’s five-set classic against Roger Federer in the 2008 Wimbledon final. Except this was a quarter-final, so the stakes felt slightly lower.
“I think is a different of kind of match. Of course, have been an emotional match. Have been I think a great level of tennis and good show. But is a quarter-final match, is not a final match. That makes a difference,” said the world No. 1 after his victory.
“Then I think all the things that happened in that final was much more dramatic than this one.”
Both players kept elevating their levels. Del Potro’s forehand was as frightening as ever, and at one point he fired one so fast, it sent Murray into uncontrollable laughter.
“107 miles an hour. That’s very funny,” said a chuckling Murray.
As the court got slipperier, both players started taking a few doubles, particularly on their net approaches. Del Potro pulled off some diving volleys that sent the crowd gasping, and he is particularly proud of one of those shots.
“I think I won the best point of the match,” Del Potro said of his small consolation. “It was great to me to play Rafa in this level.”
Nadal got the crucial break for 3-2 in the decider, utilising his drop shot perfectly to trouble the tall Argentine.
“The first two sets were really tight. Once Rafa breaks my serves, then the match becomes difficult for me,” conceded Del Potro, who hit 77 winners throughout the course of the match, compared to Nadal’s 66. “I had also my chances to break back in the fifth, and I miss some forehands. I think the key of the match was only three, four points in the end, and he took the chances.”
Nadal was told about Murray’s assessment of the fifth set, and was asked if he is able to enjoy a set like that, while he’s battling through it.
“It’s difficult to explain the feelings because, of course, you appreciate it. In some way you enjoy it. At the same time every point counts a lot. Is difficult to distract yourself thinking that you are enjoying that moment, no?” he said.
“You enjoy because at the end of the day we are playing in one of the best courts in our sport, against a great opponent, with full crowd, fifth set, great level of tennis. Of course, you have to enjoy. Is not much time to think about if you are enjoying, you are suffering. Is different feelings.”
Nadal’s reward is a place in the 28th Grand Slam semi-final of his career, and a 52nd showdown with long-time rival Novak Djokovic.
Will Nadal do anything special to recover from this near-five-hour bout with Del Potro?
“What do you want me to do, a handstand?” joked Nadal.
It’s going to be the usual for the 32-year-old – an ice bath and lots of work with his physio.
“There is no one other match in the history of tennis that played more than our match,” Nadal said looking ahead to the Djokovic clash. “That’s a big thing. We always played in important stages, important places.
“Friday is another important match against opponent that is one of the most difficult ones that you can face. He’s playing well. Only way to try to win it is play very well.”
The 25th-seeded Williams will face No. 13 seed Goerges for a second straight major, having defeated the German in the French Open third round last month.
Kerber, the highest remaining seed in the draw at No. 11, will face 2017 French Open champion Jelena Ostapenko for the first time.
The semi-finals will take place back-to-back on Centre Court starting 13:00 UK time (16:00 Dubai time), with Ostapenko-Kerber followed by Goerges-Williams.
Here’s a numbers guide to the last-four stage at SW19.
0 – sets dropped by Ostapenko this fortnight – the only semi-finalist of the four yet to drop a set. The last woman to win Wimbledon without conceding one was Marion Bartoli in 2013.
1 – Goerges is contesting her first Grand Slam semi-final.
1 – For the first time since 2015, all four women’s Wimbledon semi-finalists are seeded players.
2 – of the semi-finalists have won titles this year: Goerges (Auckland) and Kerber (Sydney).
2 – This is the first time in the Open Era that two German women have reached the Wimbledon semi-finals. The last all-German Slam semi-final was when Steffi Graf beat Anke Huber in Roland Garros in 1993.
4 – years since Jelena Ostapenko has won the Wimbledon junior title.
7 – Kerber is contesting her seventh Grand Slam semi-final, only three active players have appeared in more – Serena and Venus Williams, and Maria Sharapova.
9 – Ostapenko is attempting to become the ninth Wimbledon girls’ champion to go on and reach the women’s final, and the first since Eugenie Bouchard in 2014.
24 – return winners from Ostapenko through her five matches – the most of all players who contested the tournament.
35 – Grand Slam semi-finals reached by Williams, winning 29 of them.
36 – At 36 years and 291 days, Williams is the sixth-oldest Grand Slam semi-finalist in the Open Era. She’s bidding to become the third-oldest major finalist in the Open Era.
42 – Goerges is appearing in her 42nd major. Only four women in the Open Era played this many Slams before reaching their maiden semi-final (Likhovtseva (46), Vinci (44), Tauziat (42), Vesnina (42).
44 – Kerber has won 44 per cent of her return points against the first serve, the highest percentage among remaining semi-finalists.
44 – aces struck by Goerges this fortnight at Wimbledon, the leader among all players who contested the tournament.
79 – Williams has won 79 per cent of her first-serve points, leading the rest of the semi-finalists in this category.
84 – unforced errors struck by Williams, the fewest of the remaining players.
89 – Kerber has landed 89 per cent of her returns in, the highest percentage of all players in the women’s draw.
91 – Wimbledon main draw matches won by Williams – the most among active players. Only Chris Evert and Martina Navratilova have won more in the Open Era.
601 – minutes Goerges has spent on court so far this tournament, the most among all four semi-finalists.