Roger Federer to face Seppi in ATP Halle final

The Swiss top seed and world number two will bid for a record 15th title on grass when he meets Andreas Seppi in Sunday's final, the Italian being granted passage into the final when Kei Nishikori was forced to retire injured after just five games of the second semi-final.

Federer was forced to fend off 20 aces against Karlovic to reach the final at the event for a ninth time.

It was always going to be a slugfest with Karlovic having fired a record 45 aces past Tomas Berdych on Friday.

The Croat did not disappoint, racking up 10 aces halfway through the first set.

A sensational backhand return in the opening tie-break gave Federer the slight edge he needed on his opponent's serve and a double fault from the Croatian handed him the first set.

The Swiss again had to stay patient, but won two points on the Croatian's serve in the second tiebreak and sealed his win with a backhand volley after one hour and 28 minutes.

Seppi advanced to his second final of the year after Zagreb when Japan's Nishikori, the second seed, retired injured early in the first set.

It was the second time in two days that the Italian had gone through thanks to an injury retirement, after he reached the last four on Friday when France's Gael Monfils conceded in the second set.

Nishikori, who was moving poorly with his left leg heavily bandaged, lasted only five games before quitting.