Shanghai, China -- (Sports Network) - Fourth-seeded Russian Nikolay Davydenko defeated seventh-seeded Argentine Juan Martin del Potro in straight sets on Thursday to reach the semifinals at the $4.45 million Tennis Masters Cup.

Davydenko prevailed in 87 minutes in easy 6-3, 6-2 fashion against the 6- foot-5 del Potro, who made his Masters Cup debut this week. Davydenko went 2-1 in this week's Gold Group round-robin action and will now play in Saturday's semifinals, while del Potro settled for a 1-2 mark and is done for the week.

The gritty Russian jumped out to 4-1 leads in both sets and was never challenged on Day 5. Davydenko broke del Potro no less than four times, while allowing only one break against, and the big-hitting Argentine failed to record even one ace in defeat, compared to five for the winning Russian.

"I feel great," Davydenko said. "Today was my last chance [to get] to the semifinals. Against [Andy] Murray I have more of a chance...and against Federer, I don't know. Federer is every day [a] different guy."

Davydenko is now 2-1 lifetime against del Potro, including a 1-1 mark this year. The Argentine beat the Russian in a Davis Cup semifinal tie back in September.

The 20-year-old del Potro will represent Argentina in next week's Davis Cup final against visiting Spain in Mar del Plata. His fine ATP season featured four straight tournament titles at one point just before the U.S. Open.

In another Gold Group match on Day 5, sixth-seeded Frenchman Jo-Wilfried Tsonga picked up his only win of the week by overcoming second-seeded Serbian star Novak Djokovic 1-6, 7-5, 6-1 in 1 hour, 38 minutes on the indoor hardcourt at Qi Zhong Stadium. Tsonga popped seven aces and broke Djokovic on three occasions.

The bout marked a rematch of January's Australian Open final, which was won by Djokovic. Tsonga, however, wound up winning three of their four encounters for the year, including three straight and a victory at the Paris Masters just two weeks ago.

The 23-year-old Tsonga, like del Potro, was also making his Masters Cup debut this week. He went 1-2 in the Gold Group, while the group-winner Djokovic was 2-1 and had already booked a spot in Saturday's semis. The Serb was 0-3 in last year's round-robin portion.

The ever-improving Tsonga went 8-5 against Top-10 competition this season.

Red Group round-robin play will wrap up here on Friday when top-seeded Swiss Roger Federer (1-1) meets third-seeded Brit Andy Murray (2-0) and eighth- seeded Frenchman Gilles Simon (1-1) battles Czech alternate Radek Stepanek (0-1), who joined the field on Wednesday when fifth-seeded American star Andy Roddick (0-1) pulled out due to an ankle injury. Federer and Simon are still trying to secure a semifinal berth, while Murray has already qualified for the final four. Stepanek will not play here beyond Friday.

Murray, Simon and Stepanek, like Tsonga and del Potro, are Masters Cup rookies.

The 13-time major champion Federer, who has won the last five U.S. Opens, is a four-time overall and two-time defending Masters Cup champion. The Wimbledon and French Open runner-up beat Spaniard David Ferrer in last year's finale here in Shanghai and is the only former Masters Cup champion in this year's field.

Federer and Murray will meet in a rematch of the U.S. Open final, which was won by the super Swiss. Murray, however, is 3-2 lifetime against Federer, including a 2-1 record this season.

If Federer wins on Friday he'll move into the semis, while a loss would send him home and propel Simon into the final four.

"I'm looking forward to the match," Federer said, politely. "Should be interesting. He's a wonderful player. He's had a great end to the season. He's definitely the guy probably most in form."

The red-hot 21-year-old Murray has won 16 of his last 17 matches overall, including titles in St. Petersburg and Madrid. He's only been beaten four times since Wimbledon.