The biggest challenger to Jannik Sinner’s bid to defend his Wimbledon crown was always going to be a big Serb… just maybe not this one.With visible signs of battle, including blood stains on his shoe, the world No 1 was given an almighty scare not by 24-time Grand Slam winner Novak Djokovic but his compatriot Miomir Kecmanovic.Later in the day, Djokovic himself was also given a stern test by Chinese player Yibing Wu, who was level at 1-1 and squandered seven break points in the third and fourth sets only to eventually be outclassed physically and tactically by the veteran.The world No 50 Kecmanovic led Sinner by two sets to one and looked to have the Italian on the ropes, forcing mistakes and a worrying fall, but was ultimately beaten in a five-set thriller. Jannik Sinner is into the second round at Wimbledon – but it was a painful route in getting there Sinner’s Nike shoes were covered in blood seeping through after a fall early in the matchIt was a laborious and energy-zapping outing for the world No 1 on his first competitive appearance since he wilted in the Paris heat last month and was knocked out of the French Open in a huge second-round shock by then world No 56 Juan Manuel Cerundolo.Sinner’s right shoe was stained by red blood, which he said was not as bad as it looked, and a five-set clash of three hours and 29 minutes was rather unwelcome for a man trying to ease himself into the tournament after having time off following his Roland Garros disappointment.’I am good, (the blood) seems much worse than it is,’ he said. ‘I am surprised they let me keep playing because of the all-white (uniform guidelines)!’It was a good match from both of us so I didn’t want to disturb and take any time (with a medical time-out).’The Italian recovered well after losing the first set but Kecmanovic soon regained the lead after triumphing in some lengthy rallies on Centre Court, which hosted famous faces such as Sir David Beckham and Dame Mary Berry, both who joined in with the Mexican Wave.Sinner was in no mood for such pleasantries and feared he might soon wave farewell to SW19 after just one day of his title defence. But he soon settled and breezed through the next two sets to overturn the deficit and win 4-6, 6-3, 6-7, 6-2, 5-3. Sinner celebrates after gritting his teeth to defeat Serbia’s Miomir KecmanovicLater in the day, a couple got engaged on Centre Court and Djokovic nearly followed the gentleman in falling down on his knee as he was given a tough examination by world No 102 Yu.The Chinese player became a crowd favourite with his energetic style and soon they were chanting an elongated ‘Yu’ every time he won a point, amplified by the roof being shut and noise that seemed to rile Djokovic – though he might have mistaken the noise as him being booed.Djokovic comes to SW19 having not won a major in his last 12 attempts going back to the 2023 US Open, his first two-year wait for a Grand Slam triumph since his breakthrough years on the circuit as a teenager.Now 39, the Serb is not yet ready to quit and, with Alcaraz absent and question-marks over Sinner’s staying power after the breakdown at the last two Slams, many believe this is his last chance to win a 25th major and eighth Wimbledon crown to equal Roger Federer.This was a stern test, though, for the man who has not played since he was felled at Roland Garros by up-and-coming Brazilian Joao Fonseca.BBC viewers missed Wu take the second set as they asked punters to switch from BBC Two to BBC One, only to find they had to watch the final five minutes of Eastenders.But the action was just as dramatic in west London as it is in the fictional Walford as Wu continued to test his storied opponent. Djokovic survived a scare on Centre Court in late night action to progress through to round twoIn the fourth set, he had three break points at 3-2 up and looked certain to open up a 4-2 lead but Djokovic clawed back to deuce. Wu had another chance when he took advantage but could not capitalise again, his opponent’s experience and mentality proving stronger.Djokovic was booed as he played an imaginary violin with his racquet at the end as Wu left to an ear-splitting ovation.He said: ‘It was really challenging for me. Wu deserves a huge round of applause. I am feeling happy but not the freshest, it did not feel like the first round. ‘He surprised me with the level of every shot in his game. He did not really have a weakness, I probably should have lost the fourth set.’