Andy Murray admitted Friday's early exit from <a href="https://www.thenationalnews.com/tags/wimbledon/" target="_blank">Wimbledon</a> has impacted his motivation to continue, while defending champion Novak Djokovic motored into the fourth round with a comfortable win over Stan Wawrinka. Murray's fitness problems since winning his second Wimbledon title in 2016 have been well documented, with a hip injury threatening to end his career. However, the former world No 1 entered this year's Championships full of optimism having returned to the world's top 40 and with successive grasscourt titles under his belt, albeit on the second-tier Challenger circuit. Murray also had a favourable-looking draw at Wimbledon if he was able to get past fifth seed Stefanos Tsitsipas in the second round, but after leading the Greek by two sets to one, he was defeated after five close sets when their match resumed on Friday evening. Asked if he would be back at Wimbledon next year, Murray said: "I don't know. Motivation is obviously a big thing. Continuing having early losses in tournaments like this doesn't necessarily help with that." The defeat to Tsitsipas represented a third straight early exit for two-time champion Murray, who in 2013 ended a 77-year wait for a British male Wimbledon winner. In 2021, he was defeated by Canada's Denis Shapovalov in the third round, and 12 months ago was beaten by American John Isner in the second round - Murray's earliest ever exit. Yet, this year's elimination was arguably the biggest disappointment, considering Murray's improved form and fitness entering the tournament. "Losing in the second round, I don't find that motivating, it's not why I put all of the work in," Murray, 36, said. "It's similar to last year, I guess. I had a long think about things, spoke to my family, and decided to keep on going. "I'm unbelievably disappointed and upset now. Maybe I will feel different in a few days but right now it doesn't feel good." It was a different story for long-time rival Djokovic, though, as the seven-time champion raced against the clock to cruise past Wawrinka and into the last 16. Djokovic, chasing a record-equalling eighth Wimbledon title and record-extending 24th career Grand Slam crown, came through 6-3, 6-1, 7-6 against the 38-year-old Wawrinka. World No 2 Djokovic will face Poland's Hubert Hurkacz, whom he has defeated five times in as many meetings, for a place in the quarter-finals. Friday's win was Djokovic's 21st in 27 meetings with Wawrinka, a three-time major champion who famously defeated the Serb in the 2015 French Open and 2016 US Open finals. Djokovic never faced a break point under the Centre Court roof and completed victory just 15 minutes before the 11pm All England Club curfew kicked in, otherwise they would have had to return on Saturday. "Stan's doing an amazing job for his age – we are two old guys," said 36-year-old Djokovic who went level with Pete Sampras's mark of 31 successive wins at the tournament. "We've had great battles over the years. I respect him as a player and love him as a person. He's a really nice guy." Djokovic's win kept him on course for a final showdown with world No 1 and US Open champion Carlos Alcaraz who defeated 84th-ranked Alexandre Muller of France 6-4, 7-6, 6-3. The 20-year-old Alcaraz will face Chile's Nicolas Jarry for a spot in the last 16. Third seed Daniil Medvedev returned to complete his second-round clash against Adrian Mannarino, the Frenchman who defeated him at Wimbledon five years ago. The Russian was two sets and 4-4 ahead when play was halted on day four but quickly wrapped up victory in a third set tie-break. Danish sixth seed Holger Rune reached the third round for the first time, brushing aside Spain's Roberto Carballes Baena 6-3, 7-6, 6-4. Seventh seeded Andrey Rublev of Russia and Italian eighth-seed Jannik Sinner made the last 16 with wins over David Goffin and Quentin Halys respectively.