Brighton had not scored in their last four away games but midfielder Jake Forster-Caskey put them on the path to victory with a spectacular goal in the eighth minute.
Perseverance paid off for Rovers when Chris Brown equalised in the 74th minute after they had dominated the second half, but Brighton found their shooting boots again in the closing stages.
Lita restored the lead from close range in the 84th minute before Lopez put the issue beyond doubt with a stunning 25-yard free-kick in the dying seconds.
The home side suffered a big blow before the start when influential skipper Rob Jones was ruled out after sustaining an injury in the warm-up.
Former Manchester United apprentice Luke McCullough, originally named as substitute, came into the side for his debut with teenager Liam Wakefield drafted on to the bench.
The changes did not appear to bother Rovers as they were the brighter side at the start and Tomasz Kuszczak was the busier of the two keepers in the early stages.
James Coppinger was brought down on the edge of the Brighton box in the third minute and Mark Duffy's 20-yard free-kick sailed inches wide as Kuszczak flung himself across the goal.
But it was Brighton who snatched the lead with a goal completely out of the blue. There appeared to be no danger when midfielder Forster-Caskey picked up the ball more than 35 yards out, but he looked up before striking a stunning left-foot shot into the top corner which had Ross Turnbull beaten all the way.
Doncaster immediately tried to strike back and Kuszczak did well to punch out a 20-yard effort from Duffy following a neat build-up a couple of minutes later.
Rovers looked in trouble again in the 14th minute when Will Buckley aimed another powerful effort from 20 yards for the same spot as Forster-Caskey, but this time Turnbull reacted smartly to tip the ball over the bar.
Mistakes flowed from both sides but Brighton were having more of the attacking play and Stephen Ward should have added a second when he sent a free header wide of the mark while the home defence stood and watched following a corner.
David Cotterill fired just wide for Rovers before Coppinger set up a golden opportunity for Yun Suk-Young, but the on-loan QPR left-back placed his shot just wide of the mark when he should have scored.
Craig Conway had a snapshot saved as Brighton finished the half on top, with Rovers going in at the interval to a smattering of boos from the disgruntled home fans.
The jeers turned to cheers when Brown flipped home the free-kick from Duffy at the near post to level the scores in the 74th minute after Rovers had applied constant pressure from the start of the second half.
But it was all in vain when Albion raised their game again to snatch victory in the closing stages.
Lita, on loan from Swansea, scored a couple of minutes after coming on as substitute when he slammed the ball home from close range following a corner.
Lopez then put the icing on the cake right at the end with a swerving 25-yard free-kick that Turnbull had no chance of saving.