Wimbledon 2017: Watch highlights from the fourth day of The Championships

Roger Federer and Novak Djokovic both won in straight sets but the fourth day of The 2017 Championships was unfortunately marred by Bethanie Mattek-Sands' awful knee injury

Roger Federer and Novak Djokovic raced into the third round with straight sets wins but the day was marred by a horrific knee injury to American Bethanie Mattek-Sands, who was carried off on a stretcher during her singles match at Wimbledon on Thursday.

Seven-time champion Federer turned on the style to beat Serbian Dusan Lajovic 7-6(0) 6-3 6-2, while Djokovic needed little more than 90 minutes to beat Wimbledon debutant Adam Pavlasek 6-2 6-2 6-1.

On Court 17, Mattek-Sands was playing Romania's Sorana Cirstea when she appeared to slip as she approached the net at the beginning of the third set, then collapsed awkwardly on to the grass.

Medical personnel arrived and the 32-year-old was treated by doctors on the court for more than 20 minutes, during which time she was given oxygen and an injection.

In a mixed day for the title favourites, German top seed Angelique Kerber battled past Belgium's Kirsten Flipkens 7-5 7-5 in the second round but Czech third seed Karolina Pliskova was dumped out of the tournament.

Pliskova, who came into the championships on the back of a grasscourt title success in Eastbourne, was beaten 3-6 7-5 6-2 by 87th-ranked Slovak Magdalena Rybarikova.