Novak Djokovic keen to crash the party London: Just as John McEnroe once pursued Bjorn Borg and Jimmy Connors, so Novak Djokovic is still striving to join the conversation dominated by Roger Federer and Rafael Nadal. Yet the acclaim is growing for the seven-time major winner, who is still chasing, but also catching up. For McEnroe, indeed, despite the different eras, there have been similarities between Djokovic's recent achievements and his own struggle to gatecrash the Connors-Borg party. "That was my Nadal-Federer [comparison], and to get that respect and sort of be in that mix was something I took a lot of pride in," said McEnroe, declaring that Djokovic has now "clearly" done the same. The 27-year-old Serb this week became just the seventh man - McEnroe being one of the previous six - to complete a trio of finishes as the year-end world No.1, having not enjoyed a season to quite rival his finest but still boasting a Wimbledon title among his six so far, and the best record among the so-called Big Four since the start of 2011. After losing his first set at the ATP World Tour Finals via a tetchy 6-1, 3-6, 6-0 semi-final win over Kei Nishikori, Djokovic was scheduled to close 2014 in Sunday's decider against Federer, who twice retrieved third-set service breaks and saved four match points before beating his Swiss Davis Cup teammate Stan Wawrinka 4-6, 7-5, 7-6 (8-6) in an absorbing evening fixture at the O2 arena. This is obviously huge in the semi-finals of the World Tour Finals. It's very big," Federer said after clawing back from sudden death. Clearly, it's not the way you want to win. But I still kept my cool and tried to hang around. I got myself back into it. I was frustrated being down in the third. It was definitely a lucky escape. Djokovic had earlier become agitated with the crowd during what was also his first real test of the tournament, less than impressed to have a double fault cheered when down break point in the second set, and noting some individuals "that were going over the line throughout the whole match, some provocations that I usually don't react on but I did - it was my fault." The new father admitted at his belated media conference that he lost concentration against an improving Nishikori, citing exhaustion after a long season and a slight emotional letdown after clinching top spot the previous day. Still, at least he had far longer than Federer in which to reload and regroup for his final match of the season. "It's one of the biggest tournaments in the world, aside of the grand slams," Djokovic said. This is already the biggest possible motivation. I will try to give everything I have ... Knowing that tomorrow is the last match of the season, I'm sure that I will find any necessary drop of strength, mental and physical, to give it on the court. Federer, six years his senior, played later and for twice as long against Wawrinka; the six-time ATP championship winner also weary, but resolute. "I know it's only going to be another nine, 10 days now before I'm on vacation," said Federer, who has this weekend's Davis Cup final against France still to come. It's cool, I can handle it. The season's been long for all of us, there's no doubt. But I think Stan and myself left everything out on the court today. The senior Swiss leads Djokovic 19-17 head-to-head, having won three of their five clashes this year - not the dramatic five-set Wimbledon final, but the most recent, in straight sets at the Shanghai Masters in October. "I hope I can maybe play a little better than I played today, potentially, because I did feel the heat from Stan," second-ranked Federer said. It was tough for me to get really free‑flowing because he had the lead early, so I was running after the lead the whole time, which was tough. Wawrinka, meanwhile, will finish as the world No.4 and close his major-winning season by teaming with Federer for the Swiss team in Lille from Friday. The Australian Open champion coulda shoulda but didn't beat the legend and friend he now trails 2-15 in career contests, having surprisingly serve-volleyed on his first three match points. Match like that, you make some choice, especially when you're tired, when you're nervous. Just wanted to go for it and not wait for mistake or whatever," Wawrinka said. Today, had lot of chance. Didn't [take] them.