Rovers conceded in stoppage time to suffer a heartbreaking defeat at Oxford United.
Josh Ruffels slammed in a low shot from 25 yards in the sixth minute of added time to secure a scarcely-deserved win for the hosts.
Rovers had dominated proceedings in the second half and looked to have enjoyed a piece of justice when Ian Lawlor saved Jack Payne's dubiously awarded penalty.
But Ruffels was given far too much space to charge into Rovers territory before lashing home.
Rovers will be left scratching their heads as to how they lost a game in which they were certainly the superior side.
Jordan Houghton returned to the side after sitting out the FA Cup tie with Scunthorpe United, replacing Matty Blair who is out of action with a calf injury.
And Harry Toffolo was preferred at left back to Tyler Garratt, who dropped to the bench where Alfie May returned after two months out.
Alfie Beestin saw his strong recent form rewarded with a first ever Football League start.
A game between two footballing sides is always likely to be open and it proved that was from the start with Oxford looking to build possession while Rovers were dangerous on the counter.
Rovers pressed well in oppoition territory and caused a few mistakes in the Oxford back line.
But real chances for both sides were hard to come by.
It took 17 minutes for a shot on target with Ian Lawlor producing an excellent save. James Henry found space for a fine effort from 20 yards but Lawlor tipped the shot wide acrobatically.
John Marquis was somewhat fortunate to stay on the pitch just before the half hour mark.
As he failed to keep the ball in play out wide, he swung a boot at the shin of the full back Ricardinho. The majority of the Kassam was insensed but fortunately for Marquis, it was an incident which went unnoticed by the match officials.
It appeared as though Oxford were on a revenge mission afterwards but Marquis got the better of the battle as he made the home defence look rattled.
Attempting to give the striker close attention, Oxford only succeeding in conceding fouls or giving space to Marquis.
Soon after, Rovers had their first effort on goal when Tommy Rowe sent a header from a corner on target.
And moments later Marquis almost broke the deadlock when he met Rowe's fine cross with a powerful header which Simon Eastwood kept out and gathered at the second attempt.
Oxford had a shout for a penalty when Wes Thomas tumbled under pressure from Andy Butler after latching onto a through ball but referee Seb Stockbridge was unmoved.
Rovers started the second half superbly, showing a real high intensity and relentlessness to their play.
And they could not have come much closer to taking the lead than they did on 58 minutes.
Rowe weaved into the area past several challenges and stabbed a low shot which rattled the inside of the post and rolled along the line before trickling wide.
Brimming with confidence, Rowe went for goal again moments later, this time with a 30 yard piledriver which drew a fine save from Eastwood.
Oxford were penned into their own half as Rovers continued to push for the opening.
May was sent on to inject some pace and he found plenty of space in the channels.
The game truly ignited on 79 minutes when Oxford were awards a dubious penalty.
Payne was certainly fouled as he attempted to weave into the box but crucially, he did not cross the 18 yard line before being brought down.
Referee Stockbridge caused consternation when he pointed to the spot.
Payne stepped up and slammed low from the spot but Lawlor saved well and pounced quickly on the loose ball.
The game opened up considerably after the penalty miss but it looked certain to be heading for a goalless conclusion.
Toffolo went down injured during the initial three minutes added on but there was confusion all round as referee Stockbridge allowed play to continue into a sixth minute.
Ruffels took advantage, carrying the ball deep into Rovers territory and drilling a low shot out of Lawlor's reach and into the bottom corner.
Oxford: Eastwood; Tiendalli, Williamson, Mousinho, Ricardinho; Henry (Rothwell 61), Xemi, Ruffels, Mowatt; Payne; Thomas (Obika 80); Payne; Thomas. Subs: Shearer, Martin, Ledson, Carroll, Napa.
Rovers: Lawlor; Mason, Wright, Butler, Toffolo; Houghton; Whiteman, Rowe; Coppinger; Beestin (May 68), Marquis. Subs: Marosi, Baudry, Garratt, Kongolo, Longbottom, Mandeville.
Referee: Sebastian Stockbridge (Tyne)
Attendance: 6,711 (462 away)