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.
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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.
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