Serena Williams defended her Western and Southern Open crown, sealing WTA Tour title number 69 with a two-set win over Simona Halep in Cincinnati.

Williams' US Open preparations went off without a hitch at the WTA Premier hard-court event, losing just one set on her way to the title – with new world number two Halep unable to trouble the top-ranked American.

Halep got off to the perfect start, breaking to 15, but as the 21-time major winner Williams has done so often this week, she battled back into the match.

Consecutive breaks in games six and eight helped Williams win the final five games of the first set and an early break in the second had the local favourite on course.

Halep, however, created nine-break point chances in Williams' first two service games of the set and eventually converted to get back on serve.

The Romanian got herself out of a 15-40 hole in the seventh game, the only danger either player had of blinking thereafter as it went to a tie-break.

Williams, again, went down a mini-break, but they changed ends level at 3-3 before the champion wrapped up victory on match point number two.