SYDNEY: Usman Khawaja is relieved he finally has an Ashes Test century to savour after a "lot of carry-on" over his debut against England in Sydney seven years ago.

The elegant Pakistan-born left-hander soaked up the acclaim from his home fans after scoring 171 in the final Ashes Test at the Sydney Cricket Ground on Saturday.

Khawaja batted for 515 minutes and faced 381 balls and just missed out on bettering his highest Test score of 174 made against New Zealand in Brisbane in 2015.

It was a special milestone in the career of the 31-year-old, who has experienced many ups-and-downs throughout his 29 Tests.

"It's awesome. The SCG was where I grew up playing cricket for New South Wales and an Ashes century is something I have wanted for a long time and I haven't been able to achieve, so it was very satisfying," he told reporters.

Khawaja savoured the moment he reached his sixth Test century, pointing his bat towards his mother and wife sitting in the stands and getting a long embrace from his batting partner Steve Smith.

"He (Smith) was just telling me to enjoy it. He knows when you get a hundred you're really excited and you want to do lots of things," Khawaja said.

"Your heart's pumping and everything is going. He was just letting me know to just calm down and keep my head back down after everything to go on and make sure I got a big one."

"(It's a feeling of) elation," Khawaja added. "You don't get to celebrate Test centuries too much unless you're Steve Smith. You've got to enjoy them when they come."

Up until this match, Khawaja's biggest Ashes moment was his much-hyped Test debut in 2011 as the first Muslim to play for Australia when he scored 37 as a replacement for the injured Ricky Ponting.

"I've said a few times, that 37 was a bit embarrassing. There was a lot of carry on for a 37," Khawaja said.

"Playing in the Ashes was a dream. Did that. Winning an Ashes was a dream. We won. Scoring a hundred in the Ashes has always been something I always wanted to do. I've done that now too."

Khawaja said he hoped his century would give him more opportunities to keep a regular place in the Australian team after missing out on the sub-continent Tests.

"I love playing for Australia every single Test match, every chance I get," he said.

"All I can do is try and go out there and score runs for my team and do well in the top order."

Of the criticism directed at him from some former players, Khawaja said: "When I am scoring runs, I'm elegant and when I'm not scoring runs I'm lazy. Can't seem to win, when things aren't going well."

"It's disappointing to hear but it's something I have dealt with throughout my career," the left-hander added.

"Sometimes the game feels really simple and easy and other times it is a bit of a grind. That's the way it is."