The last time Latics played at the DW Stadium they were under Owen Coyle's watch and were three goals down against Derby inside 30 minutes.
To the visitors' credit, they refused to fold though, Neil Danns heading home early in the second half and Andre Moritz's penalty resorting parity.
But Rosler was not to be denied a winning start in the Sky Bet Championship as the brilliant McManaman steered in a 68th-minute winner.
Rosler had left Grant Holt behind for this week's Europa League excursion to Slovenia in a bid to improve his fitness and it certainly had the desired effect early.
He swept an effort away from goal after good work from Powell before the Manchester United loanee had a shot blocked himself following McManaman's purposeful probe.
It did not take too long for Latics' up-field pressing to reap rewards.
Holt was on the end of Watson's back-post cross and Matt Mills, losing the physical tussle with the former Norwich striker, saw the ball ricochet into his outstretched arm.
Referee Kevin Friend initially ignored the hosts' appeals only to point to the spot on the advice of his assistant and, from the resulting penalty, Watson fired Wigan into a 14th-minute lead.
The players were clearly feeding off the optimism a new era brings and Powell epitomised that with a glorious second.
McManaman was again involved and when Chris McCann's weak shot ballooned in the air, Powell connected with a bicycle kick which looped over Andy Lonergan in the Wanderers' goal.
It could have signalled the opening of the floodgates yet Bolton fought back.
Joe Mason's header was clawed away by Scott Carson at his near post while Moritz nodded towards goal only for Leon Barnett to clear off the line.
Then, just prior to the break, Mills almost usurped Powell's strike with a vicious scissor kick which flew just wide.
Dougie Freedman elected not to make any changes at the interval and his faith was rewarded as the Trotters pulled a goal back four minutes after the restart.
Carson did well to push Moritz's free-kick away and with the danger not cleared, the midfielder put the ball back in where Danns was on hand to halve the deficit with his head.
The visitors surged forward looking for a leveller, Moritz stinging Carson's palms from 30 yards and Danns then hitting the crossbar with a flicked header.
Wigan were rattled and they were pegged back to level terms when referee Friend equalled up the penalty count.
Lee Chung-yong went down clutching his face with Emmerson Boyce's boot raised high and Friend took his time before pointing to the same spot he had in the first period.
Boyce was livid and pushed the South Korean in the face as he lay on the floor, an action which only warranted a yellow card, before Moritz blasted home the penalty.
However, just four minutes later, Latics regained the lead.
And it was, of course, Boyce who made it, flicking a corner across the box where McManaman side-footed home.
The winger appears to have been given a new lease of life under Rosler and then beat Alex Baptiste for the umpteenth time to find Powell with a cross which the forward nodded just wide.
Chances continued to come with Mason squandering a glorious opportunity by poking wide after Moritz had slalomed through.
The Brazilian could have got another equaliser in the dying throes only for Carson to repel them once more.
- Sports & Recreation
- Nick Powell
- Andre Moritz
- Neil Danns
- Scott Carson