Madison Keys defeats Venus Williams in Aussie Open quarterfinals

Madison Keys will play in her first Grand Slam semifinal match after a gutsy, painful performance against an ageless player.

Keys battled through a leg injury to defeat No. 18 Venus Williams in the quarterfinals of the Australian Open on Wednesday. She required a medical timeout in the second set after injuring her upper left leg, but returned to beat Williams 6-3, 4-6, 6-4.

Keys will next face top-ranked Serena Williams in her first Grand Slam semifinal.

Keys called for trainer down 1-4 in second set and left the court briefly for treatment. The 19-year-old returned and promptly won a break, held serve to cut the score to 3-4 and then broke again to tie the set.

But her momentum was shortlived.

Williams, who at 34 was playing in her first Grand Slam quarterfinal match since 2010 at Wimbledon, replied with a break of her own. She then held serve to win the set as Keys walked off the court in obvious discomfort.

The final set was a slugfest between the two Americans, who combined for five breaks of serve including three in a row at one point.

Fittingly, Keys finished the match with her third break of the set.

The final numbers reflected an ugly match for both players. Keys had 45 unforced errors to 38 for Williams, but the young star also had 24 more winners, three more aces and converted seven-of-nine break point opportunities.