Uilliams scored a brace for the north eastern side, but Mike Snoei's men were resilient enough to secure a point from the tie.
Mike Snoei made a couple of changes to the side that started against Mumbai FC in the derby last weekend, bringing back Mustapha Riga and handing Mirjan Pavlovic his first I-League start, while Lalrempuia Fanai and Thongkhosiem Haokip making way for them.
Thangboi Singto, too, made two changes in the starting line-up with Lalthummawia Ralte getting the nod ahead of Vinay Singh to start between the sticks, while Jeevan Singh replaced Weilad Passah.
The first chance came in the way of the visitors, when they claimed a free-kick just outside the Pune box in the fourth minute. Boithang Haokip, who has converted a number of free-kicks this season stepped up but his shot was blocked by one of his team-mates standing in the wall.
Pune created their first opportunity in the 12th minute, when Calum Angus fed Mirjan Pavlovic with a ball on the left flank. The former Wellington Phoneix star took a quick turn and got the better of the Shillong defense before squaring it to Dhanpal Ganesh at the edge of the box. However, the midfielder failed to make a perfect contact and his shot flew above the bar.
However, it took the hosts a mere two more minutes to draw the first blood after Mustapha Riga played a through-ball to Pavlovic, who took a shot only to be blocked by Ralte. However, the ball came to Gabriel Fernandes on the rebound and the former Dempo player made no mistake in slotting the ball home.
Shillong Lajong drew level in the 26th minute, when Uilliams took a brilliant free-kick from the right and Amrinder Singh could do little to stop it from going in.
Cornell Glen had a good chance in the 39th minute, when he latched on to a long ball played from the midfield and unleashed a powerful effort to test the custodian, but this time Amrinder pulled off a good save to parry away the danger.
Just before the half-time whistle, Pavlovic showed glimpses of his class as dribbled past a number of Shillong Lajong bodies to pull the trigger, but his shot was well saved by Ralte.
Even after the break, the winter recruit of Pune FC was in the thick of things as he took two powerful shots on target in the 57th and the 58th minute, of which the first was saved by the goal-keeper and the latter rattled the woodwork and went out.
However, it was Ulliams again who scored in the 70th minute, when he controlled the ball just outside the box and took a left-footed shot to put the ball into the net after Minchol Son supplied him with a good pass.
Just when Lajong seemed to have grabbed the bragging rights, Pavlovic saved the blushes for the Red Lizards as he headed the ball home after Gurjinder Kumar headed the ball in his way from a Calum Angus free-kick.
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