(CNN) -- Five-time winner Roger Federer opened his U.S. Open account Monday with a straight sets win over Santiago Giraldo in New York. 

Despite surrendering his serve three times, the 30-year-old Swiss enjoyed a relatively comfortable match against the Colombian, ranked 54 in the world, winning 6-4 6-3 6-2 on the Arthur Ashe Stadium court. 

Leading 5-1 in the opening set, a number of uncharacteristic errors from Federer saw him squander a double-break advantage before he finally rallied to win 6-4. 

The second and third sets were more straight-forward, though the world number three will be concerned about his winners-to-unforced errors ratio -- he finished with 36 winners and 35 unforced errors. 

"It was quite up and down, getting used to the conditions," admitted Federer, in quotes carried by usopen.org. 

"I don't think I've ever played my best in the first round but it's important to come through them and come up with a good feeling." 

Home favorite Mardy Fish was ruthlessly efficient as he easily dispatched Germany's Tobias Kamke 6-2 6-2 6-1. 

However fellow American Ryan Harrison was not so fortunate. The 19-year old lost out to big-serving Croat Marin Cilic, 6-2, 7-5, 7-6 (8/6). 

Seventh seed Gael Monfils ruined the U.S. Open debut of Grigor Dimitrov of Bulgaria with a battling 7-6, 6-3, 6-4 victory, while Czech Tomas Berdych, the number nine seed, beat French qualifier Romain Jouan 6-2, 7-6 (7/4), 6-1. 

Elsewhere, French 13th seed Richard Gasquet trounced Ukrainian Sergiy Stakhovsky 6-4 6-4 6-0, Serbian Janko Tipsarevic ousted France's Augustin Gensse 6-2 7-5 6-0, while Czech Radek Stepanek beat Germany's Philipp Kohlschreiber 6-4 6-1 6-3. 
Who does he defeat?
 win over Santiago Giraldo in New York. 
