ATP Finals: David Goffin thrashes Dominic Thiem to reach semi-finals in London

Belgian seventh seed David Goffin completed the semi-final line-up at the ATP Finals with victory over Austrian fourth seed Dominic Thiem in London.

Goffin won 6-4 6-1 to secure second place in the Pete Sampras Group and set up a semi-final against Roger Federer at 14:00 GMT on Saturday.

"It will be a tough match, so nice to play a semi against him," said Goffin.

Bulgaria's Grigor Dimitrov will face American Jack Sock in Saturday's other last-four contest at 20:00.

Dimitrov beat Pablo Carreno Busta 6-1 6-1 in the last of the round-robin matches on Friday, but with the qualification scenario settled they were only playing for 200 ranking points - and the £145,000 prize money for a match win.

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'It's never easy to play against a friend'

Goffin won 18 out of 19 points as he dominated the latter stages of the first set

Fourth seed Thiem produced a desperately disappointing performance with the prize of a semi-final place at the season finale on offer.

He began in suitably focused fashion, winning a punishing 32-stroke rally on his way to establishing a 3-0 lead, but Goffin would win 12 of the next 14 games.

A double-fault from the Austrian handed the break back in game five, one of 15 straight points Thiem conceded as he started to spray errors from the baseline.

There was a chance to re-establish himself in the set with Goffin serving for it at 30-30, but Thiem leaked a forehand pass wide and the set was gone when Goffin slammed a forehand winner down the line.

After a brief delay for attention to a bloodied knee, Thiem continued to struggle badly in the second set.

By the time he fired a backhand wide to miss a third break point at 4-1 down, he had racked up 22 unforced errors.

Goffin remained steady and patient, coming through that game in 11 minutes for a 5-1 lead and closing out the victory with a backhand winner after an unexpectedly swift 71 minutes.

"It was a pity to play against Dominic, he is such a good friend and a nice guy, it's never easy to play against a friend," said Goffin.

"It was tough, I was focused, I knew I had to stay calm and be ready for a tough battle. At the end I was happy with the way I managed the match."

It was an impressive response from the Belgian, who beat a struggling Rafael Nadal in his opening match before taking just two games against a rampant Dimitrov.

"After the first match against Rafael I wasted so much energy, I was not ready for Grigor, but I had a good rest yesterday and was ready for today, and I hope I can do the same for the semi-finals," added Goffin.