Second seed Andre Agassi edged past Max Mirnyi 7-6 6-3 in the second round of the Madrid Masters on Tuesday.
The 34-year-old American fought off five break points in the first set but edged a tiebreak 7-5 before easing to victory over the Belarussian.
"He plays a type of game that is very difficult," said Agassi. "It was tough to get a rhythm."
In other second-round action, fourth seed David Nalbandian of Argentina beat Sweden's Robin Soderling 7-6 6-3.
Agassi, who was
playing his first match since his US Open quarter-final
loss to Roger Federer, added: "I think he was outplaying me in the first set and I got
fortunate on some key points."
Also in the second round, ninth seed Pavel Andrei saw off American Mardy Fish and France's Antony Dupuis downed 12th seed Juan Ignacio Chela of Argentina 7-6 6-3.
Earlier, Tommy Haas made light work of Belgian opponent Xavier Malisse to reach the second round.
The German triumphed 6-4 6-1, while Spanish teenage Davis Cup hero Rafael Nadal eased to a 6-2 6-1 win over Italy's Davide Sanguinetti.
In other first-round matches, American Taylor Dent beat Mikhail Youzhny 6-3 6-2, Spain's Fernando Verdasco defeated Sweden's Jonas Bjorkman 6-1 6-2 and Argentine Guillermo Canas won 5-7 7-5 6-1 over Kristof Vliegen of Belgium.
Agassi will next play either 14th seeded American Vince Spadea or the 18-year-old, who Nadal needed
only an hour to dismiss Sanguinetti.
"Against Spadea, I'll certainly have to do better than I
did today," said Nadal, who was the star of the Spanish
side that beat France last month to reach the final of the
Davis Cup against the United States in December.
"I hope to play 50% better each day," said Nadal. "Clearly, winning the first match gives me a lot of
confidence."
Withdrawals by Roger Federer, Andy Roddick and Lleyton
Hewitt have left Briton Tim Henman as the top seed, followed by Agassi and Russia's Marat Safin.
Spain's Albert Costa faces Henman in the second round on
Wednesday.
"It'll be very difficult," said Costa. "We've played
each other a lot. I've beat him, he's beat me.
"But he's in
better form than I am. I'll go out with nothing to lose and
under no pressure."
The winner of the tournament will collect £250,000 and 100 points towards qualification in the Champions Race.
The event has attracted publicity for swapping ballboys and girls for models
"They did it very well. I didn't notice any difference," said Costa.
He added: "It's
entertaining, and I like the idea that the tournament should do this."
But a senior Spanish government
official insisted it was sexist.
"Soledad Murillo ... considers that this move contributes to
building a clearly discriminatory vision of women, as simple
objects of decoration and entertainment," the Labour and Social
Affairs Ministry, where Murillo works, said in a statement.
Agassi added: "I think it is important for our sport to understand its
product clearly, and I'm not quite convinced this is part of our
product.
"It was difficult, to say the least, to concentrate on the
ball, but I suppose I had an advantage - I'm used to playing
with my wife [Steffi Graf].