Thursday 22 October 2015 08:06, UK
Fourth-seeded Jo-Wilfried Tsonga was made to work hard by 37-year-old Tommy Haas before making progress at the Erste Bank Open in Vienna on Wednesday.
The Frenchman, who has rediscovered his best form after reaching the final of the Shanghai Masters last week, came through 6-3 6-7 (3-7) 6-4 in a match between two former champions of the event in the Austrian capital.
Tsonga's reward is a clash against Czech world No 78 Lukas Rosol for a place in the quarter-finals.
Eighth-seeded Fabio Fognini also advanced to the second round after beating Paul-Henri Mathieu of France 6-4 3-6 6-3 and will next face wily Czech Radek Stepanek.
Ernests Gulbis upset third-seeded John Isner 6-4 4-6 6-4 to reach his third quarter-final of the season and all but end the American's chances of making the season-ending ATP World Tour finals in London.
In a match dominated by strong serving, Latvian Gulbis hit 23 aces against Isner's 16. Each set was decided by just one break though both players had to fight off six break points.
Gulbis, who was on a five-match losing streak coming to this tournament, will next play seventh-seeded Ivo Karlovic or Sergiy Stakhovsky.
Second-seed Kevin Anderson proved too strong for home hope Andreas Haider-Maurer.
The South African, who reached the quarter-final stage at this year's US Open, won 6-4 7-5. He will next face 22-year-old Czech Jiri Vesely.
In the final match of the night, seventh-seeded Ivo Karlovic won a tight battle against Sergiy Stakhovsky 6-4 7-5 to reach the quarter-finals.
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