The French Tsonga (1-1) doused the American Fish 7-6 (7-4), 6-1 on the indoor hardcourt at The O2 Arena in London. Tsonga broke Fish's quality serve five times and popped seven aces among his 33 winners in prevailing in an hour-and- a-half.
Fish is now all but eliminated here at 0-2.
Tuesday's marquee match will pit second-seeded former world No. 1 Rafael Nadal (1-0) against his great rival, fourth-seeded former top-ranked star Roger Federer (1-0). The Swiss icon upset the powerful Spaniard in last year's Tour Finals finale here in London. Nadal bested Federer in this year's French Open title tilt.
The 25-year-old Nadal is 17-8 lifetime against the 30-year-old Federer.
The five-time World Tour Finals champion Federer is riding a 12-match overall winning streak, including back-to-back titles in his native Basel and at the Paris Masters. The 16-time Grand Slam champion is tied with Pete Sampras and Ivan Lendl for the most titles at this prestigious event.
In Group A round-robin play here on Wednesday, current world No. 1 Novak Djokovic (1-0) will meet seventh-seeded 2007 Tour Finals runner-up David Ferrer (1-0) and third-seeded Aussie Open runner-up Andy Murray (0-1) is scheduled to face fifth-seeded former Wimbledon finalist Tomas Berdych (0-1). Djokovic was the Tour Finals champion back in 2008 and is the reigning U.S. Open, Wimbledon and Aussie Open titlist.
Djokovic is an amazing 70-4 this season.
This exclusive event features only the top-eight players in the world. Round-robin play will be staged through Friday, while the semifinals will be held on Saturday and the lucrative final will be played Sunday. The top-two finishers from each group will compete in the semis.
This week's big winner will earn at least $770,000. An undefeated champion would pocket $1.63 million.