It was a diamond formation on display at Brisbane Road, with Tom Huddlestone sitting deep and flanked by Jermaine Jenas on the right and Steed Malbranque on the left, with Keane operating in the space behind Bent and Dimitar Berbatov.
Bent nearly made a mark on proceedings as early as the fifth minute after Jenas prodded the ball into his path. The striker darting to the right of the penalty area before rasping in a shot that fizzed over the bar.
Jenas did well to squeeze back in a Keane corner, which Stuart Nelson did not deal with any degree of comfort, but then managed to block bravely when Berbatov was poised to smash home.
It was the perhaps unlikely figure of Paul Stalteri who came a fingertip away from opening the scoring on 15 minutes when Malbranque picked out his purposeful run and the full-back skipped past his marker and unleashed a power drive that Nelson did brilliantly to tip over.
Against the run of the play it was Orient who did take the lead. Jason Demetriou's whipped cross was connected with by the head of Adam Boyd and the ball looped over the despairing leap of Paul Robinson.
The advantage lasted less than a minute due to Malbranque speeding down the left and applying a low centre that was eventually fired home by Keane from close range after the ball took a couple of diversions along the way. It was a busy 18th minute in E10.
It was the team in all white dictating the ebb and flow of the game as the contest approached half-time without a huge level of urgency from the two teams, although Huddlestone did nearly liven up events with a low drive that skidded just past the left hand upright and Bent found the net only for his effort to be ruled out for offside.
Radek Cerny, Wayne Routledge and Jermain Defoe were introduced after half-time, swapping with Robinson, Berbatov and Malbranque.
The boys began to ease through the gears and it was Younes Kaboul charging forward from the back and locating Bent that led to the lead being restored. Bent jinked around Nelson, only for Tamika Mkandawire to clear off the line. In the next passage of play the defender was fouled by Murray and a penalty was awarded which Keane duly converted on 56 minutes.
It became three on the hour when Huddlestone slipped the ball through to Defoe, who thumped home with his left foot from around the edge of the penalty area.
Defoe turned provider five minutes later when he was the supply line for Bent, who latched onto his pass ahead of Nelson to poke into the net and make it 4-1.
More chances followed and Defoe found the net again, only for the flag once again to halt another celebration. The second half carried a lot more cut and thrust and Orient responded with late goal through substitute Efe Echanomi.
Two goals from Robbie Keane and one each from Jermain Defoe and Darren Bent sealed a 4-2 victory over Leyton Orient at Brisbane Road on Wednesday evening.After the shock of falling behind, the boys responded, levelled ahead of the break and cut loose in the second half before a late Orient reply