Six-time champion Roger Federer will play Alejandro Falla in the final of the Gerry Weber Open after they won their semi-finals.
Federer fired 10 aces and defeated the fourth-seeded Kei Nishikori 6-3, 7-6 (4) as he improved his tournament record to 45-5.
Nishikori rallied to force the second set to the tiebreak, where he made a mini-break at 4-2, only to let Federer off the hook with two consecutive forehand errors.
After a first-round bye, Federer began his Wimbledon preparations by defeating Portugal's Joao Sousa then had a walkover in the quarter-finals.
Falla rallied to beat 2011 champion Philipp Kohlschreiber 5-7, 7-6 (5), 6-4 to become the first Colombian to reach the final of a grass-court tournament.
"It's an amazing feeling," Falla said. "I knew I had good chances here. I already played great matches on grass courts. It's my favorite surface."
The final against seven-time Wimbledon winner Federer will be Falla's second on tour after he finished runner-up to Ivo Karlovic at Bogota in 2013.
Dimitrov upsets Wawrinka
Fourth-seeded Grigor Dimitrov upset top-seeded Stan Wawrinka 6-2, 6-4 to reach the final at Queen's Club in England.
He will play 10th-seeded Feliciano Lopez in the final, after the Spanish left-hander defeated Radek Stepanek of the Czech Republic 7-6 (7), 6-4.
It was the first victory in their three meetings for Dimitrov, who at 23 is the youngest player ranked in the world's top 20.
The Bulgarian took a 3-2 lead on his fourth break point when Wawrinka double-faulted, then broke again for 5-2.
"It was not my best match," Wawrinka said. "Didn't serve the way I wanted, and didn't move well. But Grigor was playing well, being really aggressive, serving big and mixing a lot."
Despite his defeat, Wawrinka was happy with his preparation for Wimbledon, which begins in nine days.