Federer is grouped with Gaudio, Lleyton Hewitt and Carlos Moya

The world number one, returning after six weeks on the sidelines, needed just 91 minutes to beat his Argentine opponent 6-1 7-6 (7/4).

Rain halted the match after only six minutes, but following a two hours and 20 minute delay it was one-way traffic.

Federer lost only one point on his serve in the opening set and sealed the win on his first match point.

Steady drizzle in Texas meant it was the only match to be completed on the competition's first day.

Federer squandered 12 of 14 break points against Gaudio but was pleased to return to winning ways.

"It was very satisfying for me," he said. "I'm happy with my game, not only after six weeks of no tournaments but two weeks of not playing tennis at all.

"I missed a lot of opportunities in the second set, but to beat a player like Gaudio was satisfying and I can build on it and try to keep it going."

Gaudio said: "It's a tough competition and I still hope to win a match."