LONDON — David Goffin is into the last four of the ATP Finals, to go any further he'll have to do something he's never done before: beat Roger Federer.
The No.7-seeded Goffin beat Dominic Thiem 6-4, 6-1 at the O2 Arena on Friday to set up a semifinal meeting with Federer.
From 0-3, 0-15 down in the opening set, Goffin won 15 consecutive points to take control of the match, and never looked back.
"I've never found a key to beat Roger," said Goffin, who has lost all of his six meetings with the 19-time Grand-Slam champion. "Honestly, I don't know what to do tomorrow. But I'm going to try something, something different, something that I've never done in the past."
The victory took Goffin to 2-1 in the round-robin stage of the elite season-ending tournament after a win over Rafael Nadal and defeat to Grigor Dimitrov, who will meet Jack Sock in Saturday's other semifinal.
Dimitrov defeated Pablo Carreno Busta 6-1, 6-1 in the late match to become the first player to win all three round-robin matches on debut since Andy Murray in 2008.
Unlike during his 74-minute thrashing by Dimitrov on Wednesday, Goffin was able to recover from a slow start.
Thiem produced some blistering groundstrokes to break in the second game of the match and held for a 3-0 lead, but from there his game disintegrated.
"Well, I had a very, very good start obviously," Thiem said. "Again, some very bad mistakes. I let him back into the game. Somehow after the 3-0, I lost it until the end."
When Thiem finally ended his opponent's run of five straight games, Goffin kept his composure to serve out the set. Thiem then received treatment on his left knee, but it didn't seem to help.
He was broken again in the third game of the second set and then twice more as Goffin cruised to victory.
Goffin was far from faultless himself, with both players' unforced error totals doubling their winner counts.
However, in the major moments Goffin was able to keep his game under control, taking five of his seven break point opportunities. Thiem was wasteful, completing just one of his six.
"As soon as I came back at 3-3 with a good service game, I knew that he was struggling a little bit with his groundstrokes," Goffin said. "He was hitting too hard maybe a little bit. He lost his timing in his backhands. He started to think about how to hit the ball."
Goffin is making his full debut at the event, having stepped in as an alternate for one match last year.
Reaching the semifinals in London is the latest step in a groundbreaking season for the Belgian. He broke into the top 10 for the first time in February and reached a career high No. 8-ranking earlier in November.