Despite plundering a superb treble in the Papa John’s Trophy on Tuesday night, the striker was dropped at MK Dons.
Instead John Marquis was once challenged to provide the cutting edge for a Blues side desperately short of League One goals.
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And Cowley has explained why he elected not to retain Harrison in his line-up.
He told The News: ‘Ellis played on Tuesday, he hasn’t had a background of games.
‘It would have been greedy for him to have played 90 minutes on Tuesday and then to start on Saturday.
‘Particularly against MK Dons, who are so equipped in possession, ask you so many questions defensively and look so big on you.
‘Physically it would have been a big challenge for Ellis – and John has been a big part of our
defensive work, there is no doubt about that.
‘To be fair to him (Marquis), he’s the first to put his hand up in the dressing room and say the attacking end of the team has to do better.
‘I thought we created enough to win a game of football away from home, but we didn’t quite manage to execute the final action.
‘John had a good shot in the second half, a good pass from Marcus played him in down the side.
‘We have worked hard on them in training, those types of runs and those types of chances, that's what we have to keep doing.
‘When we don’t score, we have to keep battling away, we have to keep working at it.
‘We have to accept the criticism that comes our way and have big enough shoulders to be able to cope with that and keep pushing them on the training ground to find a way of scoring.’
Marquis has now returned one goal in seven appearances as his frustrating Pompey form continues.
Nonetheless, he was last season’s top scorer with 18 from 49 appearances in all competitions.
Meanwhile, George Hirst was dropped from the 18-man squad entirely on Saturday.
The loanee from Leicester was handed his full Blues debut in the 4-3 loss at AFC Wimbledon on Tuesday night.
Yet at MK Dons, Cowley preferred to have Harrison as his sole centre-forward on the bench, with Gassan Ahadme also absent.
He added: ‘George travelled with us, but wasn’t in the 18.
‘We now have 22 players and that means we have everyone fit at the moment. We’re working hard to try to get people physically prepared and physically ready.’
A message from the Editor, Mark Waldron
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