ESTORIL, Portugal, April 15 (UPI) --
World No. 1 Roger Federer
, still trying for his first tournament win in 2008, advanced to the second round Tuesday at the Estoril Open in Portugal.
Federer dropped the first set but battled back to eliminate Belgian Olivier Rochus, 4-6, 6-3, 6-2, slamming 17 aces in the match.
The Swiss star next plays Victor Hanescu of Romania.
Davydenko cruised past Austrian Jurgen Melzer, 6-3, 6-1, for his eighth straight match victory.
In a couple of upsets, Portuguese wild card Rui Machado topped Coatian Ivo Karlovic, who retired with a leg injury, and Germany's Denis Gremelmayr beat Finn Jarkko Nieminen.
Other winners included Hanescu, Joao Sousa of Portugal, Czech Jiri Vanek, Italian Flavio Cipolla and Frenhmen Thierry Ascione and Florent Serra.
© 2008 United Press International, Inc. All Rights Reserved. Any reproduction, republication, redistribution and/or modification of any UPI content is expressly prohibited without UPI's prior written consent.