Frances Tiafoe produced the comeback of the week at the Terra Wortmann Open, saving three match points to beat second seed Felix Auger-Aliassime in a deciding-set tiebreak and reach the semifinals in Halle. He was not the only American through: Taylor Fritz avenged last Sunday's Stuttgart final by edging Ben Shelton in a three-tiebreak rematch, while top seed Alexander Zverev came past qualifier Raphael Collignon and wild card Daniel Altmaier added another scalp, knocking out fourth seed Daniil Medvedev. Saturday's semifinals pair Zverev with Fritz and Altmaier with Tiafoe.
Tiafoe saves three match points to stun Auger-Aliassime
Frances Tiafoe came through the longest match of the day, beating second seed Felix Auger-Aliassime 3-6 6-3 7-6(12) to reach the semifinals. It was a win built in the rallies rather than on serve. Auger-Aliassime took the first set on a single break and fired 25 aces across the match, but won just 39% of points behind his second serve, and once the points went past the first strike Tiafoe was the better player. He saved break points in two separate games to take the second set and force a decider, then recovered from 2-0 down in the third to reach a tiebreak that turned into the match of the tournament. Tiafoe saved three Auger-Aliassime match points and took his fifth, edging it 14-12 as a thunderstorm rolled in over the arena. The Canadian's serving kept him in front for long stretches, but a count of 48 unforced errors to 15 winners told the story of where the match was decided. It is one of the biggest wins of Tiafoe's season, and sends him into a semifinal against Daniel Altmaier.
Fritz avenges the Stuttgart final against Shelton
Taylor Fritz gained quick revenge for last Sunday's Stuttgart final, beating Ben Shelton in a grass-court battle to reach the semifinals. The fifth seed earned his first win over a top-10 opponent this season, in a match that could hardly have been finer: all three sets went to tiebreaks, neither player dropped serve, and both held all 18 of their service games. The contrast in styles ran throughout, Fritz the more structured and disciplined player, Shelton leaning on explosive shot-making and aggression. For long stretches it felt like a continuation of the Stuttgart final, Fritz a touch more solid before Shelton raised his level in the biggest moments, but this time the American turned the script around. Shelton played the cleaner first-set tiebreak, Fritz answered in the third, and the second-set breaker proved decisive: Shelton held a match point but missed a forehand, and Fritz escaped to take control. The numbers caught the margins, with Fritz striking 24 aces, winning 80% of points behind his first serve and finishing with a 52% share of total points. On a surface where a handful of points decide everything, he was the steadier man.
Zverev sees off Collignon
Alexander Zverev reached the semifinals, but qualifier Raphael Collignon made the top seed work harder than the rankings suggested. In another match shaped by serve and first-strike tennis, not a single break was recorded, sending both sets to tiebreaks. The Belgian brought real resistance and intensity, and the first tiebreak was the tense one, Zverev edging it 12-10 after working out of an awkward spot. The second was the only passage where the gap showed, the German racing through it 7-2 from the start. Zverev's experience proved decisive, but Collignon again justified his run from qualifying. The world No. 3 finished with 14 aces, won 81% of points behind his serve and took 53% of the total points, advancing without serious trouble while still having to hold a high level.
Altmaier comes back to stun Medvedev
The upset of the day belonged to Daniel Altmaier. After his comeback over Hubert Hurkacz earlier in the week, the German wild card produced a bigger surprise by knocking out fourth seed Daniil Medvedev in three sets. More than the result, it was the level of his grass-court tennis that stood out on a surface that has rarely brought him much success, combining aggressive shot-making with composure in the biggest moments, and his recent work with grass-court specialist Dustin Brown may be part of it. Altmaier took the opening set, weathered Medvedev's response in the second, and produced his best tennis in the decisive phase. He finished with 15 aces, won 76% of points behind his first serve and was effective on return, taking 56% of points behind the Medvedev second delivery. In a match separated by just two total points, Altmaier was sharper when it mattered, reaching a first home semifinal.
The semifinals: Zverev meets Fritz, Altmaier faces Tiafoe
The first semifinal pairs top seed Alexander Zverev with Taylor Fritz, a meeting that reads like an early final. Zverev arrives on the confidence of his Roland Garros title and home support in Halle, but recent history sits with Fritz, who has won the last six meetings between them, including grass-court encounters at Wimbledon in 2024 and Stuttgart in 2025. Fritz has built through both weeks on grass and now has back-to-back ATP 500 semifinals to show for it. With both serving well, the margins are likely to be small.
The other semifinal is the unlikely one. Wild card Daniel Altmaier, who has now taken out Hubert Hurkacz and fourth seed Daniil Medvedev on a surface that has rarely suited him, meets Frances Tiafoe, through after saving three match points against Auger-Aliassime. Neither was expected this far, and both arrive on the back of long three-set wins.