Melbourne, Jan 21 : Maintaining his ruthless start to the season, Rafael Nadal defeated Karen Khachanov 6-3, 6-2, 3-6, 6-1 on Friday to reach the fourth round at the Australian Open for a staggering 15th time. Before January, Nadal had not competed in a tour-level event since Washington in August due to a foot injury. But the sixth seed is playing as if he has never been away, with his victory over Khachanov extending his perfect 2022 record to 6-0. "It is a very special week for me, coming back. Every single time I am able to play here is very special. Tonight I played against a great player and a good friend on Tour. It was my best match since I have come back without a doubt," Nadal said in his on-court interview. The Spaniard eased through the first two sets under the lights on Rod Laver Arena but Khachanov threatened to turn the match on its head when he took the third. However, Nadal moved ahead again early in the fourth, celebrating exuberantly when he broke serve and went on to claim a fine victory after two hours and 50 minutes. The 35-year-old Nadal is aiming to win a record-breaking 21st Grand Slam title in Melbourne, having lifted the Australian Open trophy in 2009. He fired 39 winners and committed 30 unforced errors to improve to 8-0 in his head-to-head series against Khachanov. "I have gone through some very tough times over the past year. But nights like tonight mean everything. I keep fighting and going every day. I put a lot of effort into being back where I am today, so I am happy," Nadal added. The World No 5 will next play 18th seed Aslan Karatsev or Frenchman Adrian Mannarino in the last 16. Only Roger Federer (18) has advanced to the fourth round at Melbourne Park more times than Nadal. /IANS