Cliff Richard surprises fans with a capella rendition of 'Summer Holiday' at Wimbledon

NOTE: Skip forward to the 10-minute, 45-second mark for Cliff's performance.

Day seven of Wimbledon kicked off yesterday afternoon, with an extra special surprise for audience members ...

In celebration of Centre Court's centenary, the legendary Sir Cliff Richard performed an a capella rendition of his hit song, 'Summer Holiday.'

The 81-year-old's routine paid tribute to Wimbledon lore, to when he spontaneously entertained the crowd in the '90s due to rain halting play.

Broadcasters Sue Barker and John McEnroe also partook in the celebrations.