The Dens Park side went down to their Championship opponents after an early goal from Jackson Longridge.
Under the glare of the live cameras, McCann had hoped to see his side building on last Saturday’s comprehensive 4-0 win away at Stirling Albion, but instead they disappointed their modest home support and the dejection was compounded by an injury to Sofien Moussa, their influential Tunisian striker.
“I’m really disappointed”, said McCann. “We made warnings to them all week about Ryan Wiliamson bombing down the right-hand side and we didn’t deal with it for the first goal.
“There’s a few things that I’m not happy about today. The pitch was too long and sticky. But that being said, I thought we were still off the pace. It’s still early in the season but we can’t use it as an excuse because Dunfermline are at the same stage as us and they came away with the win today.
“The boys know I’m unhappy with them and I expect a reaction against Peterhead in midweek.
“We’ve got a few injury worries for that one. We’ve not been able to fully look at Moussa’s injury but it appears that it’s a muscle injury rather than an impact one which is not good news for us.”
From the start, it was unclear which of the two sides plays their football in the top-flight.
Dunfermline started with real intent and pace going forward. The goal, which arrived after two minutes, typified their early belief as right-back Williamson surged to the byline and crossed for his opposite full-back Longridge to bullet a header into the net.
The Pars looked sharper, quicker and stronger than the hosts for long parts of the first-half and could’ve doubled their advantage midway through the first period when the lively Myles Hippolyte was freed behind the Dees defence. Unfortunately for him his tame strike was easily saved by Jack Hamilton.
Dundee also had to suffer the blow of losing their captain and main goal-scoring threat, Moussa. He was carried off on a stretcher with what looked like a back injury.
There was a slackness to the Dens Park side’s play throughout the afternoon. Their best opportunity came from distance: the energetic Elton Ngwatala turned and sent a thumping drive smashing off the crossbar.
The win puts the Pars in pole position to top Group D and manager Allan Johnston was understandably delighted.
“It was a really good performance from start to finish,” he said. “We got the ideal start and then we knew they were going to come at us but I think we restricted them to very few opportunities and we always carried a threat on the break too.
“I thought the boys worked incredibly hard today. There was a selflessness to their play. They all worked for the team and I think we can get even better.”