Top-seeded American Andy Roddick reached the quarter-finals of the 600,000-dollar hardcourt SAP Open on Thursday with a 6-3, 7-6 (7/3) victory over tenacious Latvian Ernests Gulbis.

After cruising through the first set, Roddick found the going tougher in the second as Gulbis stretched the match to 1hr 21min.