David Ferrer and Andy Murray continued their push for a place at next month's ATP Tour Finals in London with opening-round wins at the Valencia Open.

Murray beat Ferrer in the Vienna final last weekend to climb above his rival into eighth place in the race for the O2 Arena, with the top eight set to qualify.

Ferrer is the top seed at his home tournament and opened his challenge for a fourth Valencia title with a 6-3 7-5 victory over Andreas Seppi.

The Spaniard looked at ease in the opening set, but then allowed Seppi to gain the edge in the second, with the Italian 5-3 up and serving for the match.

However, Ferrer produced a timely break of serve and then followed that up with another in game 12 to set up a meeting with compatriot Fernando Verdasco.

Third seed Murray, a wild card in Valencia, also progressed through in straight sets, but made hard work of his match with Jurgen Melzer.

In a contest that contained nine breaks of serve, countless unforced errors and a warning for Melzer for smashing his racquet as frustration threatened to bubble over for both players, Murray held the edge to win 6-3 6-3 in 81 minutes.

Victory in Valencia, where Murray also won the title in 2009, would see the Briton climb up to fifth in the rankings and all but assure him of a place in London.

Thomas Berdych's hopes of reaching the ATP Finals suffered a setback with an opening-round defeat to home hopeful Pablo Andujar.

The second-seeded Czech had lifted the title in Stockholm just three days ago, but was outplayed by Andujar in a 6-3 6-2 result. Berdych curently lies a vulnerable seventh in the race for London.

Russia's Mikhail Youzhny saw the defence of his Valencia title ended at the first hurdle with a 7-5 6-3 loss to Brazilian qualifier Thomaz Bellucci.

Meanwhile, Serena Williams admitted she was embarrassed by her crushing 6-0 6-2 defeat to Simona Halep at the WTA Finals in Singapore, her heaviest loss in 16 years.

The world number one, an 18-time Grand Slam winner, was 16 when she last suffered such a thrashing.

Halep, the 23-year-old from Romania, took apart her opponent's serve in the first set, allowing the American to win just six points on serve on the way to breaking three times.

Williams improved marginally in the second set, carving out six break points, but Halep saved them all and took her two break opportunities to seal a famous win.

The American said: "It was actually embarrassing I think describes the way I played. Yeah, very embarrassing. I've seen her play a lot. Like I said, she's never played like this before. My serve was at best in the ten and under division in juniors."

Williams, 33, last failed to win more than two games in a completed match back in 1998 when she lost 6-1 6-1 to Joannette Kruger in Oklahoma City.