Bulgaria’s Grigor Dimitrov steamrolled Pablo Carreño Busta 6-1, 6-1 in just over an hour here to remain undefeated at the ATP Finals and give himself a further dose of confidence heading into this weekend’s action.

The World No.6 came out swinging freely at the O2 Arena here on Friday night in the final Group Pete Sampras round-robin match, a contest that was a mere formality since Dimitrov had already clinched the top spot in his group and his Spanish opponent had already been eliminated from semi-final contention, reports Efe.

The Bulgarian won 11 straight points to start the contest and quickly breezed to a 5-0 lead against his shell-shocked opponent.

Carreño Busta finally got on the board 21 minutes into the match, but Dimitrov finished off the first set with a fourth straight easy service hold.

The Spaniard’s misery was compounded early in the second set, when he took a tumble near the net while trying to chase down a passing shot and then received treatment from the trainer on several occasions for an apparent hip adductor injury.

Dimitrov continued to outclass his opponent over the final few games, clinching the comfortable win when his rival hit a forehand wide of the sideline on match point.

The Bulgarian had lost to Carreño Busta earlier this year on clay at the French Open, but he leveraged his bigger weapons and greater variety to dominate Friday’s match-up on an indoor hard court.

“I wanted to keep on going with the style that I’ve been doing so far … I followed my game well and didn’t make mistakes. I think the simplicity helped me to play such a good game, to go through those matches in such a manner,” Dimitrov was quoted as saying on the ATP Finals’ Web site.

Dimitrov barely scraped past Austria’s Dominic Thiem 6-3, 5-7, 7-5 on Monday, but he shifted into a higher gear to rout Belgium’s David Goffin 6-0, 6-2 on Wednesday and then trounce Carreño Busta.

Friday night’s victory gave Dimitrov an additional 200 ranking points and leaves him just 160 points behind third-ranked German Alexander Zverev.

With a victory over Jack Sock in Saturday’s second semi-final, Dimitrov can ensure a top-three finish in the year-end rankings for the first time in his career.

But Dimitrov was cautious ahead of a match against an opponent he has lost to on three of four occasions, most recently at this year’s Indian Wells event.

“He is not an ordinary player. He really uses his strengths very good. I think he obviously has improved a lot in his game, played pretty much throughout the whole year, very strong finish of the year, won the (Paris Masters). Obviously he’s riding on confidence right now,” Dimitrov said.

Earlier Friday, Goffin booked a spot in the last four of the ATP Finals with an easy 6-4, 6-1 victory here Friday afternoon over fourth-ranked Austrian Dominic Thiem.

Thiem stormed out to a 3-0 lead but then proceeded to lose 15 consecutive points and five games in a row. The Belgian subsequently wrapped up the first set in 31 minutes with an outstanding running forehand passing shot.

The Austrian, who was clearly struggling with left-knee discomfort, held serve in his opening service game of the second set but then dropped the final six games of the contest.

Goffin will square off in Saturday’s first semi-final against Swiss six-time champion and world No. 2 Roger Federer, who was the top finisher in Group Boris Becker.

Federer and Dimitrov are the only two semi-finalists to reach that stage without dropping a match. The Swiss has lost two sets and 36 games through three matches, while the Bulgarian has lost just one set and only 19 games.