Simona Halep opened her WTA Finals campaign by cruising to a 6-0 6-3 victory over US Open champion Flavia Pennetta on Sunday.

The Romanian is - in the absence of reigning champion and world number one Serena Williams - top seed for the season-closing tournament in Singapore and looked good value for that billing.

Pennetta got the better of Halep when the pair met in the semi-finals at Flushing Meadows earlier this year but, looking for revenge, the world number two wrapped up the first set in just 25 minutes.

A single break late in the second proved to be enough for 2014 runner-up Halep to clinch victory.

"I started the match really well," said Halep. "I played my best in the first set, fast, smart and aggressive.

"It became a tough match, though. Every match here is like the final of a Grand Slam - I played the semi-finals with Flavia in the US Open.

"I knew she'd play better and the second set was much tougher."

Halep was playing her first match since retiring from the China Open injured a fortnight ago and added: "I was injured a little bit in China, my Achilles, but now I'm feeling good

"I had treatment and a break before coming here, and now I'm playing without pain, so that's good. I'm just hoping to be okay during the matches, though, because I didn't play official matches until now."