World No1. Roger Federer delivered another polished performance to beat Andreas Seppi in straight sets in the semi-final of the ATP World Tour event in Rotterdam.

Federer, who has won the title twice before, was not at his fluent best but was seldom troubled after breaking the Italian early in the first set and proved too good on all the big points to coast to a 6-3 7-6 (7-3) victory.

The Swiss will play world No.5 Grigor Dimitrov in Sunday’s final, bidding to win a 97th career tournament.

The 36-year-old guaranteed his return to the top of the world rankings on Friday after more than five years, becoming the oldest man to reach the summit.

In the other semi-final, David Goffin was forced to retire against Dimitrov after suffering a freak eye injury.

The 27-year-old Belgian dropped the first set 6-3 but was 1-0 up in the second when he framed an attempted volley directly into his left eye and was unable to continue.

Dimitrov immediately ran around the net to check on him.

Goffin left the court for treatment and five minutes later the umpire informed Dimitrov that he had won through retirement.

It was not clear how serious the injury was.