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 improved to 2-0 lifetime against Fish by breaking the American's quality serve five times and popping seven aces among his 33 winners in their hour-and-a-half affair.
Fish, slowed by a left hamstring injury here, is now all but eliminated this week at 0-2.
Murray (0-1), meanwhile, lost to David Ferrer (1-0) in straight sets here on Monday in a match where he was slowed by a groin injury and pulled out of the tournament on Tuesday.
The British Murray captured five titles this year and was the runner-up at the Australian Open.
Alternate and world No. 9 Janko Tipsarevic has replaced Murray in Group A.
Tuesday's marquee Group B match in London 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. 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 on Wednesday, current world No. 1 Novak Djokovic (1-0) will meet the seventh-seeded 2007 Tour Finals runner-up Ferrer and fifth-seeded former Wimbledon finalist Tomas Berdych (0-1) will battle Tipsarevic, who will make his debut at this prestigious tournament.
Djokovic was the Tour Finals champion back in 2008 and is the reigning U.S. Open, Wimbledon and Aussie Open titlist. He is an amazing 70-4 this season.
This lucrative 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 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.