Connor McBride had an instant impact off the bench to help Rovers Under-23s to a convincing victory over Leicester City in tough conditions in Leyland.
The Scot emerged off the bench to hit two goals in three minutes after the returning Joe Grayson had earlier given Rovers the lead with a cushioned finish.
There was still time for the excellent McBride to get an assist to his name, teeing up Luke Brennan for Rovers' fourth in a terrific second half performance in the rain.
After an even first 45 minutes, Rovers came to life in the second half and ended up blitzing a Leicester side that contained ex-Rovers youngster Callum Wright in their starting XI.
For Rovers, Daniel Ayala appeared for an hour in the encounter for his first competitive minutes in nine months, whilst there was a long-awaited return for Grayson, who replaced the Spaniard for the final 30 minutes, with the defender back in action after a year out with a troublesome hamstring injury.
Elsewhere, there were starts handed to first team trio John Buckley, Harry Chapman and Jacob Davenport in a bid to boost their match sharpness.
Rovers started the game well, with Sam Burns dragging wide of Jakub Stolarczyk's right-hand post after only nine minutes played at a drizzly County Ground.
Dan Pike's tantalising ball into the box then caused havoc in the Leicester box soon after, but Burns and Brad Lyons saw efforts blocked before Chapman curled over the upright.
At the other end, Ali Reghba slammed over from 15 yards when he really should have tested Andy Fisher in the Rovers goal midway through the half in City's only notable chance of the first 45 minutes.
The deadlock almost arrived early into the second half, but Stefan Mols could only head straight down and into the gloves of Stolarczyk after getting on the end of Lewis Thompson's cross from the right.
Rovers continued to probe for the opener, but Chapman's strike was too close to the Leicester goalkeeper after Louie Annesley's high ball found him in behind the visiting backline.
A mistake from Annesley led to a rare opportunity coming City's way, but after Mitchell Clark and Reghba played a one-two, the former could only smash high over Fisher's goal and the scoreline remained the same.
Clark was busy at the other end to hack off the line after some lovely Rovers build up play. Buckley was the orchestrator and fed Thompson down the left flank. His cross-shot was pushed out by Stolarczyk, hit Chapman and was creeping into the back of the net until Clark was there to save the day.
It appeared that the goal was coming, and it did arrive just a moment later through Thompson's shot deflecting off Grayson and in.
Chapman's corner kick missed everyone, but Thompson was lurking at the back post to volley towards goal and in via a clip off Grayson with 21 minutes remaining.
It was just what Rovers deserved after looking the side most likely of scoring after an improved second half display.
Barr made his second change on 76 minutes, with McBride entering the action in place of Burns, and the Scot nearly made an immediate impact, but could only slam wide.
However, McBride wasn't to be denied and scored his second goal of the season in fine style with only 10 minutes remaining.
Good running off the ball from Chapman opened the space up for the forward, who capitalised on an error from Sam Hughes to confidently sweep past Stolarczyk and double the lead.
Better was to come for the substitute, as he finished off another flowing move in style. Chapman played in Dan Pike, and his pull back was perfect for McBride to smash into the roof of the net from close range to make it 3-0.
Soon after and McBride turned provider for another substitute, showing intelligent play and unselfishness in setting up Brennan to emphatically thump home a fourth of the night.
The win continues Rovers' 100% record in the league following the narrow win over Manchester City last time out.
Next up for Barr's boys is another home test against Manchester United Under-23s on Friday 2nd October, kick-off 2pm at the County Ground.
Rovers Under-23s: Fisher, Pike, Ayala (Grayson, 60), Annesley, Thompson, Lyons, Buckley, Davenport, Mols (c) (Brennan, 82), Chapman, Burns (McBride, 76).
Unused substitutes: Eastham, Whitehall.
Goals: Grayson, 69, McBride, 80, 83, Brennan, 90.
Leicester City Under-23s: Stolarczyk, Daley-Campbell, Clark, Hume (Flynn, 59), Hughes (c), O'Connor, Shade (Arlott-John, 72), Leshabela, Reghba (Suengchitthawon, 78), Wright, Tavares.
Unused substitutes: Bosworth, Nelson.
Booked: Wright, 42