LONDON, July 9 (Reuters) - Berating the umpire at the start and bellowing to the sky as he closed out a third-set tiebreak on Centre Court, it was hard to argue with Novak Djokovic's assertion that the passion is back. The three-times Wimbledon champion continued to look much more like his old self as he recovered from an early wobble to beat unpredictable Latvian Ernests Gulbis 6-4 6-1 7-6(2) and take his place in the fourth round for a 10th time. "Obviously when you're playing well, then you're feeling well, then you're even more motivated, passionate to see how far it can take you," 30-year-old Djokovic told reporters. His former coach Boris Becker, commentating for the BBC, had picked up on Djokovic's feisty on-court mood, saying it was a sign that the 12-times grand slam champion was emerging from a 12-month funk that began after winning the 2016 French Open. "Boris knows me very well. So he's right when he says that the passion is back. I've been feeling better on the court," said Djokovic, who will next face 51st ranked Frenchman Adrian Mannarino, who he beat in last year's second round. Djokovic dropped his serve in the third game when Gulbis let rip with three clean winners and was clearly not happy with the work of American umpire Jake Garner and was clearly heard to tell the official to "focus". "Maybe it wasn't right me doing that and I apologise," Djokovic said. "He is trying to do his job as best he can, as am I. Sometimes it can just be said in the heat of the match." LAST CHANCE Former top-10 player Gulbis, now ranked 589 after several injuries, said after his second-round win over Argentine Juan Martin del Potro that he was on the "last chance train" in his bid to return to the top of the game. He started like an express train too. Three whistling winners left Djokovic standing as he broke and Gulbis looked dangerous when leading 4-2. But it all went wrong quickly and Djokovic went on to win the next nine games with some clinical tennis. Gulbis did recover in the third set and pushed the former world number one hard, stretching the contest to a tiebreak. Djokovic was in no mood for overtime, though, and when Gulbis dumped a volley out at 1-3 the Serb let out a hearty roar before celebrating the next point with a similar verbal volley. "I'm delighted, I raised my level of tennis today compared to the first two rounds," Djokovic said. "This was the most focused I've been on the court for the last couple of weeks."