Juan Martin Del Potro faces veteran Tommy Haas in the quarters of the Erste Bank Open in Vienna on Friday.
Del Potro produced an accomplished performance to see off Philipp Petzschner in the second round, beating the German 6-3, 6-4.
"I think I played much better in this match than last week (in Stockholm)," Del Potro said. "I need to play better to win more matches. He was a tough opponent in the first round. I enjoyed the atmosphere and the last point - probably the best of the match - was a good way to win."
Del Potro has compiled an impressive 43-14 win-loss record on the tour this year and currently lies 13th in the Race with an outside chance of making the ATP World Finals. He was relieved to get his indoor season up and running after a surprise early defeat in Sweden last week to James Blake.
Haas won the Vienna title way back in 2001 and a decade on, the German is into the last eight after seeing off fifth seed Juan Ignacio Chela and Slovenian qualifier Aljaz Bedene.
Prediction: Del Potro in two.
