NEW YORK (Reuters) - Serena Williams overpowered German Carina Witthoeft 6-2, 6-2 to set up a third-round clash with big sister Venus at the US Open on Wednesday (Aug 29).

Williams sent down 13 aces and 30 winners to record her second consecutive straight-sets victory at Flushing Meadows as the 36-year-old, who is hunting a record-equalling 24th Grand Slam title, wrapped up the win in one hour and seven minutes.

"It's always such a great crowd at night. It's just amazing to play in front of this crowd," she said court-side after her victory. "I was happy with a lot of things."

Next up is a 30th career meeting with Venus, who beat her younger sibling in their most recent encounter at Indian Wells earlier in 2018.

The last time the two sisters met at a Grand Slam was in the 2017 Australian Open final, where Serena prevailed in straight sets.

"It's obviously a tough match," Serena added.

"It's so young in the tournament, but it is what it is. It's not the end of the world. We would rather have met later. We're both going to come out per usual and play our best in front of you guys.

"Normally, I would say cheer for me. But, whoever you are feeling - me or Venus - will work."