Sydney, Feb 2 (Reporter) A dominant performance with the bat against Sri Lanka in Galle has left Australia with plenty of ponder ahead of the World Test Championship Final. Stand-in Australia captain Steve Smith is backing in-form batter Usman Khawaja to prolong his international career and maintain his opening role for this year's ICC World Test Championship Final and upcoming Ashes series. Khawaja scored his highest Test score during Australia's crushing victory over Sri Lanka in the first Test in Galle, with the left-hander contributing a vital innings of 232 to move into the top five leading run-scorers for the current World Test Championship cycle. While Khawaja recently turned 38 and is facing a fresh battle from the likes of teenager Sam Konstas to maintain his place at the top of the batting order ahead of a busy upcoming Test period, Smith sees no reason why the veteran can't continue in the role for as long as he wishes, an ICC report said. “He’s still batting exceptionally well and age is only a number,” Smith said of Khawaja. “He’s still doing everything right, he’s catching well in the slips, he’s a senior figure. He’s batting really well. I’m not a selector, but I’m sure as long as he wants to play then I’m happy with him there for sure," Smith said. “Batting at the top of the order at the moment, particularly in Australia, is as hard as I’ve seen in my career. The amount of seam movement, and you throw into that he’s facing Jasprit Bumrah throughout the summer with a brand new ball, fresh every time. There’s probably not a much bigger threat in world cricket at the moment or almost ever," he said. “He’s batting nicely, it’s just tough at the moment. Fortunately here the last few times he’s played on the sub-continent, he’s come with such a clear method, a really effective method and stuck to it for long periods. He’s tough to set a field to when he’s able to manipulate the field,” Smith said. While Khawaja's spot at the top of the order seemingly looks locked in for the World Test Championship Final in June against South Africa, Australia face a fresh selection headache as they try and squeeze all their best players into their XI for the one-off Test. Konstas shown enough during the Border-Gavaskar Trophy series to put his hand up for selection, debutant Josh Inglis threw his hat into the ring with a century on debut against Sri Lanka, while star batter Travis Head looked in great touch in a relatively unfamiliar role alongside Khawaja as opener. Injured all-rounder Cameron Green also returned to the batting crease at training in Australia and is in contention to take on the Proteas as a batter only should selectors opt to recall the highly-talented 25-year-old. The conditions expected at Lord's for the one-off final will be vastly different to what the Aussies faced against Sri Lanka in Galle, but confidence is high within the Australian camp and Smith thinks his side can continue their winning run if they can maintain their excellent form. "To post 650 on what was a wicket that offered a fair amount of spin, was a very good effort," Smith noted. "It was a near-flawless performance," he added...////...