LONDON (Reuters) - Daniil Medvedev’s ATP Finals debut last year proved to be a chastening experience as he suffered three defeats but on Monday the Russian made his mark with an opening win against 2018 champion Alexander Zverev.The 24-year-old’s 6-3 6-4 win put him joint top of the Tokyo Group alongside world number one Novak Djokovic, who put on a masterclass to trounce debutant Diego Schwartzman 6-3 6-2. Medvedev will face Djokovic on Wednesday and will take heart from the fact that the Serb also lost all three of his group matches on his debut in 2007 but returned a year later to beat Nikolay Davydenko to claim the title in Shanghai. Djokovic has won four more titles since the event moved to London in 2009 and, judging by the way he clicked smoothly into gear on Monday, will take some stopping as he bids to equal the six of Roger Federer. Medvedev will not be short of confidence though after a superb display against Zverev who once again struggled to control his serving gremlins. “I actually didn’t know that he (Djokovic) was 0-3 in his first appearance,” Medvedev, who also beat Zverev to win this month’s Paris Masters, told reporters.