Rovers suffered their first defeat of pre-season but will have been heartened by the manner of their performance against a strong Birmingham City side.
Che Adams netted three minutes from time for the Championship outfit, who took away the spoils from the fixture staged at Solihull Moors.
But Rovers will have taken away plenty themselves as they arguably deserved a positive result against a near full strength Birmingham.
The major plus point of the night from a Rovers perspective was the returns of Tommy Rowe and James Coppinger, who impressed on their comebacks from injury.
While the previous fixtures were focused primarily on fitness, this outing was the first real opportunity to search for indications as to what McCann's thinking may be for the start of the season in a fortnight's time.
The Rovers boss had pledged to give as many players as possible a full 90 minutes on this trip, with the senior members of his squad who did not feature set for the same treatment at Grimsby Town on Tuesday.
McCann had hinted that the sides to face Grimsby and then Sheffield United next Friday would perhaps offer some insight into his thoughts of a strongest XI.
And one glance at the teamsheet for the clash with Birmingham provided a decent indication.
WIth new signings Mallik Wilks and Ali Crawford absent, as well as big names John Marquis and Andy Butler, it was enough to suggest those not involved were closer to the front of McCann's mind than those who were.
Nonetheless, the group that did feature did their best to alter the thinking of the boss as they went toe-to-toe with a strong Birmingham out.
Gary Monk fielded the strongest possible team at his disposal, with strong Championship operators Lukas Jutkiewicz, Che Adams and Jota providing the threat.
It looked set to be an evening on the back foot for Rovers as Birmingham began the game strongly, dominating possession and pushing the visitors back onto their own 18 yard line.
The Blues spread passes across the pitch but, credit to Rovers, found few openings to really probe.
Mitchell Lund was called upon to make a vital clearance in front of his own goal as Maxime Colin looked to play in Jutkiewicz.
And Jota flashed a low shot past the post after cutting in from the left.
After standing up to the early pressure, Rovers enjoyed a strong period themselves.
And by the end of the first period, they could comfortably claim to have had the better half.
They kept possession very well, flooded men forward and pressed very hard when they did not have the ball.
If McCann needed any further evidence the fitness work of the previous weeks had paid dividends, he had it from an energetic performance which lasted from start to finish.
McCann's players took the opportunity against the strongest opposition faced so far in pre-season to show further development of his work with them.
Movement, particularly in advanced areas, was very good with five or six players pushing forward when Rovers moved up the pitch.
Key to plenty of the good play in the first period was the returning Rowe, making his first appearance since undergoing hamstring surgery late last season.
He demonstrated the range of passing and smart runs of which Rovers fans have become accustomed.
Rovers grew in confidence and Alfie May arguably should have done better when played into space after a surging run from Alex Kiwomya.
Rowe sent in a wonderful first time ball from the left which May was inches away from connecting with when Michael Morrison blocked.
While Rovers largely controlled possession, chances were few and far between for both sides for the remainder of the half with Jacques Maghoma going closest with an awkward effort from 20 yards which bobbled past the post.
Half time saw the introduction of James Coppinger, who played on the right of the front three with Issam Ben Khemis dropping back into midfield.
Ben Khemis went close early in the half with a dipping volley.
The second period was a much more even affair with both sides enjoying chances.
Jota continued to be a lively presence for the hosts and saw an effort deflected narrowly wide after a mazy run.
Adams looked to have given Birmingham the lead when he latched onto a misplaced pass at the back and slotted past Marko Marosi, only for the assistant to flag for offside.
Marosi was subbed off soon after, replaced by youngster Louis Jones who produced a stunning one-handed save to tip away a header from Jutkiewicz.
Garratt was well placed and brave to make a trio of smart blocks, throwing himself in front of a shot from Kristian Pedersen and heading at point blank range from a Jota drive.
Kiwomya looked to seal the game for Rovers as he ghosted across the face of the box and smashed a shot which Connal Trueman palmed away.
And Coppinger looked to catch out Trueman with a shot from distance but it dipped just over the bar.
Rovers' own resolve was finally broken three minutes from time.
Jones made a fine save from a snap shot but parried straight to Adams, who took a touch and slotted in low.
The goal was somewhat unfair on a Rovers side that had worked hard and largely kept quiet a strong opposition from a higher division.
It may not have been McCann's strongest team but the performance given will have given the new manager great heart as the season fast approaches.
Birmingham (4-4-2): Trueman, Colin, Morrison, Dean, Pedersen; Jota, Gardner, Kieftenbeld (O'Keefe 77), Maghoma; Adams, Jutkiewicz. Subs: Bernard, Weaver, Seddon, Lubala, McFarlane.
Rovers (4-3-3): Marosi (Jones 62), Lund (Horton 88), Wright, Garratt, Amos, Blair, McCullough, Rowe (Coppinger 46), Ben Khemis (Prior 70), May (Gibbons 88), Kiwomya. Subs not used: Morris, Watters.
Referee: John Brooks