Roger Federer, Novak Djokovic and some of the most known faces of the tennis world took the London tube ahead of the start of the ATP Finals in London on Sunday.The season’s final ATP event is all set for a start in the London O2 arena but ahead of that the tennis stars decided to have a little fun on the public domain.Sighting tennis stars like Federer and Djokovic is a rarity but some of the commuters of the London tube came across this opportunity suddenly and surely would not have complained.”Although we’ve probably all ridden on the tube a time or two, this was very different. It’s a very cool way to make an entrance. There were quite a few surprised looks on the faces of folks, especially when Roger and Novak walked by. It was a pretty cool treat for them,” John Isner was quited as saying by the ATP World Tour website.ATP shared videos and photos of the journey these stars had in the tube and it sure like it was a fun-filled time spent.It wasn’t just our #NittoATPFinals doubles players that hopped on to the London Underground this evening! #Selfie #Londonisopen pic.twitter.com/9ewxS76rAkATP World Tour (@ATPWorldTour) November 9, 2018The name’s Federer………Roger Federer. pic.twitter.com/4Dx4AYy0eJATP World Tour (@ATPWorldTour) November 9, 2018So @rogerfederer where are we going? #NittoATPFinals #Londonisopen pic.twitter.com/dcN5vrpWG6ATP World Tour (@ATPWorldTour) November 9, 2018Alexander Zverev’s no-socks appearance was one of the highlights of the fun evening with Marin Cilic decided that the style is “Sascha” and is not for [email protected]_marin has decided that the no socks’ combo isn’t for him #Marinsfashionworld pic.twitter.com/UWFNQ5aVK3ATP World Tour (@ATPWorldTour) November 9, 2018Roger Federer and Novak Djokovic are the top billings in the eight-man event and are also placed in different groups increasing their chances of a final meet.Group Lleyton Hewitt consists of Federer, Kevin Anderson, Dominic Thiem and Kei Nishikori while Group Guga Kuerten comprises of Djokovic, Zverev, Cilic and John Isner.Federer is aiming for a 100th career ATP title in London and going by the early judgements, his prime thorn will be Djokovic. Federer won his 99th ATP title in Basel, his home and bid for his 100th in Paris before he ran into Djokovic in the final, which extended his wait.Djokovic, on the other hand, has had a sensational return to form since the Wimbledon. After scooping the Wimbledon title, Djokovic has won the Cincinnati Masters, US Open, Shanghai Masters and Paris Masters, making him the hot favourite to win the ATP Finals title.Zverev, who has been touted as the Gen Next leader has won three Masters title so far but is yet to shine at the Grand Slam stage. Cilic, Anderson, Nishikori and Thiem are all Grand Slam finalists but topping Federer and Djokovic in London might be a huge ask of them.