Ahmedabad, March 9 : A scintillating unbeaten century from Usman Khawaja helped Australia finish day one of fourth Test on a commanding 255/4 against India at the Narendra Modi Stadium on Thursday. After Australia elected to bat first on a nice batting pitch, Khawaja kept his calm, played late and with soft hands to hit 15 fours in his unbroken 251-ball stay at the crease to notch up Australia's first century of the tour. He had useful partnerships of 61, 79 and 85 with Travis Head, Steve Smith and Cameron Green, who remained unbeaten on 49 off 64 balls at stumps, and helped Australia get a slight upper hand in the match. The final session began with India's persistence paying off as Steve Smith tried to push defensively off Ravindra Jadeja. But he got an inside edge onto the pad, and was hard enough to dislodge the stumps. Peter Handscomb tried to be the enforcer with delightful back-to-back boundaries off Umesh Yadav's short balls. But his promising stay at the crease came to an end when Mohammed Shami beat Handscomb's outside edge to send the off stump on a cartwheel ride. Khawaja and Cameron Green capitalised on fuller deliveries from Ashwin and Jadeja to hit five boundaries collectively, before India took the new ball from 81st over. In the first over with a new ball from Umesh, Green was comfortable in cutting and driving off him. Shami's delivery on pads was tucked by Khawaja through square leg, while Green pulled and drove through mid-off to take two boundaries in the 85th over. Khawaja got his 14th Test century by clipping Shami through square leg, with a wide smile and leap of joy showing his happiness on reaching three-figure mark at the stroke of stumps. Brief Scores: Australia 255/4 in 90 overs (Usman Khawaja 104 not out, Cameron Green 49 not out; Mohammed Shami 2/65, Ravindra Jadeja 1/49) against India /IANS