The Irish heartthrob was among the tennis fans who watched Novak win the World Tour Finals over Rafael Nadal at the O2 Arena in London on Monday (11 November).
Unlike most fans, however, lucky Niall got to hang out with Novak after the match and shared a picture of their meeting via Twitter.
Niall added the caption: "I had the best night at the @ATPWorldTour #finalshowdown , congrats to @DjokerNole on a fantastic win."
'Best Song Ever' singer Niall jetted over to London after spending a few days with his family in his Mullingar, Ireland hometown. While chilling out at home he attended the Christening of his godson and nephew Theo and treated us to a very sweet snap of him cuddling the tiny tot.
Niall is having some downtime following One Direction's humongous world tour and insanely busy year. The five-piece finished their 'Take Me Home Tour' in Japan earlier this month having begun it in London way back in February.
Next up for the group will be in the inaugural 1D Day, taking place 23 November, just two days before their new album Midnight Memories is released.
The jam-packed day will see Niall, Louis Tomlinson, Liam Payne, Zayn Malik and Harry Styles conduct a seven-hour broadcast with fans from live in Los Angeles, featuring celebrity guests and other fun activities.
Watch One Direction's video for 'Story Of My Life' below: