Wawrinka posts another round-robin win in London

London, England ( - Rising Swiss Stanislas Wawrinka notched his second round-robin win of the week Friday at the season-ending $6 million ATP World Tour Finals.

The seventh-seeded slugger improved to 2-1 for the week by overcoming third- seeded Spaniard David Ferrer 6-7 (3-7), 6-4, 6-1 on Day 5 at London's O2 Arena. Wawrinka won in 2 hours, 19 minutes, launching 14 aces and breaking Ferrer's serve six times. Ferrer settled for only two breaks and zero aces in defeat.

Wawrinka still has a chance of reaching the semifinals this week, while the 2007 Tour Finals runner-up Ferrer is eliminated from semifinal contention after going 0-3 in round-robin play.

Friday's other match will pit world No. 1 Rafael Nadal (2-0) against fifth- seeded Tomas Berdych (1-1) in a rematch of the 2010 Wimbledon final, which was captured by Nadal. If Nadal wins on Friday, Wawrinka would join the mighty Spaniard in the semis from Group A.

Nadal has already secured a berth in Sunday's semis here.

This week's four-player Group A features the U.S. and French Open champion Nadal, the Roland Garros runner-up Ferrer, Berdych, and Wawrinka.

Group B is comprised of second-seeded Australian Open titlist Novak Djokovic (2-0), fourth seed Juan Martin del Potro (1-1), sixth-seeded 17-time Grand Slam winner Roger Federer (1-1), and eight seed Richard Gasquet (0-2). Saturday's del Potro-Federer winner will advance to the final four at this prestigious eight-player event.

Djokovic has already captured Group B and secured a berth in the semis this weekend. The red-hot Serbian star has won his last 19 matches overall on tour, including a title last week at the Paris Masters, where he topped Ferrer in the finale.

The two-time Tour Finals titlist Djokovic beat the six-time winner Federer in last year's marquee final at The O2.

Djokovic and Federer are the only former champions in this week's field. Nadal (2010), Ferrer and del Potro (2009) have finished as Tour Finals runners-up.

Round-robin play will be staged through Saturday, with the semifinals on Sunday, and the final on Monday. The top-two players from each group qualify for the semis.

An undefeated champion this week would earn $1.923 million.