Roger Federer continued his march towards a record-extending ninth Gerry Weber Open title in Halle by reaching the final where he will play home star Alexander Zverev.
The world No 5, building up to an assault on an eighth Wimbledon title in July, was made to sweat in his 13th consecutive semi-final by young Russian Karen Khachanov, before coming through 6-4 7-6 (7-5) in one hour and 25 minutes of action.
Federer, 35, has yet to drop a set after four matches in Halle this week, although his victory over the rapidly rising talent of the 21-year-old in their first meeting was a huge test of his credentials.
"I thought it was extremely close, especially that second set. I'm still just very happy how I was able to close it out in the tiebreaker," said Federer who first reached the Halle final in 2003.
Fourth seed Alexander Zverev, who upset Federer 12 months ago, set up a mouthwatering final after fighting back against Richard Gasquet to seal a 4-6 6-4 6-3 triumph.
The talented world No 12, who is chasing a fourth ATP title of 2017, will now face Federer in a repeat of their semi-final from last year - a match which the 20-year-old German won in three sets.