Federer is trying to win his fifth title in Hamburg
Defending champion Roger Federer kept up his good form on clay with a comfortable win over Spain's Fernando Verdasco at the Hamburg Masters.
The world number one, who has won in Estoril and finished runner-up in Monte Carlo in the last month, won 6-3 6-3.
Federer will face Andreas Seppi, who beat Nicolas Kiefer 6-3 5-7 7-5.
Third seed Novak Djokovic saw off Albert Montanes 6-2 6-3 and will now take on Rafael Nadal, who thumped fellow Mallorcan Carlos Moya 6-1 6-3.
The in-form Serb will take over Nadal's number two world ranking if he wins.
I'll just play the match as any other one
"I'll just play the match as any other one and try to stay focused," said Djokovic.
Nadal, the French Open champion the past three years, has spent a record 147 weeks ranked second behind Federer dating back to July 2005.
"If you want it's a little bit more important than a normal Masters semi but it's not as special as if you were playing for the number one," said the Spaniard.
Federer is a four-time champion in Hamburg and got his only win to date over Nadal on clay in last year's final.
In a straightforward quarter-final, Federer benefited from a Verdasco ankle injury midway through the second set and the Spaniard gave up a double-fault on match point.
"I think I played well today," said Federer. "Fernando is one of those players you have to be always very careful of.
"He was a little bit more predictable today but made less unforced errors.
"That was his choice of tactics - I'm not sure if it was the right one."
Federer has played the 24-year-old Seppi just once, coming through a tight match at the Monte Carlo Masters last year in straight sets.
Italy's Seppi crushed the hopes of the home crowd by beating Germany's Kiefer in a three-hour thriller.