Youzhny, the No. 3 seed, beat Sijsling 6-3, 6-2 in 68 minutes. He won three-quarters of the points on serve and saved the only two break points he faced.
Youzhny dropped just three points when he landed his first serve.
First-round play was completed Wednesday, including a match in which sixth-seeded Marcos Baghdatis beat Tobias Kamke 6-7 (6-8), 6-2, 6-4. Baghdatis saw just one break point -- and saved it -- while taking 74 percent of the points when serving. He lost four points on serve in putting the match away in the third set.
Also advancing to the second round was Flavio Cipolla, who was tied 1-1 in the first set when eighth-seeded Lukas Lacko retired with a back injury. Youzhny beat Lacko in last year's Zagreb final.