Vienna - Jo-Wilfried Tsonga shook off jet lag to defeat 37-year-old Tommy Haas 6-3, 6-7 (3/7), 6-4 on Wednesday to reach the Austria Open second round and keep his World Tour Finals hopes alive.
French star Tsonga only arrived in Vienna on Tuesday night after losing the Shanghai Masters final against Novak Djokovic on Sunday.
He overcame 32 unforced errors, counter-balanced by 41 winners and five breaks of serve, to deny Haas, playing on a 466th ranking after coming back from a third shoulder surgery.
"I arrived in Europe, and had had two nights at home in Switzerland," said Tsonga.
"When I got here on Tuesday night, I had a hit on the court before going to the hotel.
"During the match, I was really tired, especially during the second set. But Haas is not playing his best yet.
"I struggled but I held on for the win. It was good to win, but I need to recover for the next round."
Tsonga, seeded fourth, is in the mix for one of two remaining places in the eight-man field at the World Tour Finals in London from November 15.
He stands provisional ninth with Vienna top seed David Ferrer holding eighth behind Japan's Kei Nishikori.
Haas said that he is already looking ahead to 2016 when he will be playing for at least the first half of the season with a protected ranking due to his injury comeback.
But his defeat by Tsonga still stung.
"How can you be happy when you lose? It's never a good feeling. But I'm pleased that I'm still playing good tennis. I have a lot of work to do though," said the former world No 2.
SA'S ANDERSON ADVANCES
Second seed Kevin Anderson began with a 6-4, 7-5 win to eliminate the last Austrian, Andreas Haider-Maurer, a victory punctuated by 19 aces from the big South African.
Unpredictable Latvian Ernests Gulbis out-aced John Isner 23 to 16 in a 6-4, 4-6, 6-4 knockout of the American third seed to reach the quarter-finals.
The defeat meant that Isner's already slim chances of qualifying for the eight-man field in London took a major hit as the provisional 12th-placed candidate was beaten.
Gulbis, who has ridden a ranking roller-coaster in his patchy career, currently stands at a humble 117th in the world.
The Latvian son of a millionaire businessman improved to 3-2 over Isner, who had won their last two meetings.
Gulbis went up an early break in the final set and held the edge until the end.
ATP all-time serving king Ivo Karlovic beat Sergiy Stakhovsky 6-4, 7-5 with the seventh seed firing a mere 10 aces.
In a first round match, Italy's eighth seed Fabio Fognini defeated Frenchman Paul-Henri Mathieu 6-4, 3-6, 6-3 in the pair's first meeting since 2009.
Results on the third day of the Austria Open on Wednesday (x denotes seeded player):
Ivo Karlovic (CRO x7) bt Sergiy Stakhovsky (UKR) 6-4, 7-5
Ernests Gulbis (LAT) bt John Isner (USA x3) 6-4, 4-6, 6-4
Fabio Fognini (ITA x8) bt Paul-Henri Mathieu (FRA) 6-4, 3-6, 6-3
Jo-Wilfried Tsonga (FRA x4) bt Tommy Haas (GER) 6-3, 6-7 (3/7), 6-4
Kevin Anderson (RSA x2) bt Andreas Haider-Maurer (AUT) 6-4, 7-5