Serena Williams faces Mona Barthel on Thursday in Round 3 of the Western & Southern Open in Cincinnati.  The match starts at 9 p.m. ET.  Watch the live stream HERE.

World No. 1 Williams survived a scare on Wednesday when Eugenie Bouchard won the first set.  Williams bounced back and ultimately won (4-6, 6-2, 6-2), but the dropped set is a reminder that anything can happen.

"It was just some crazy tennis out there today," she told WTATennis.com after the match.  "It was just really different conditions than last week in Toronto - I always forget it's so different here.  So it probably took me a while to get used to it."

There's extra impetus for Williams to win the Cincinnati Masters - it's one title she doesn't have.

"Apparently I've done well here once - I got to the semifinals, but it was a smaller tournament back then," she said.  "I have to get used to these conditions because this is a tournament I don't have.  If I play like today, I'll continue not to have it."

Williams must get past World No. 32 Barthel to remain in contention for the title.  The 23-year-old German is 22-17 with one WTA singles title this season.  She lost in the first round at Roland Garros and the second round at Wimbledon.

She retired in the second round at Bad Gastein with a right shoulder injury, but has appeared to recover from it - she dropped Lucie Safarova in the first round (6-3, 6-4) and Maria Kirilenko in the second round (6-4, 6-4) at this year's Cincinnati Masters.

Thursday will be the first meeting between Williams and Barthel.

*Stats via WTATennis.com and MatchStat.com.