The Blues suffered a 2-1 defeat at Millwall last night to exit the Carabao Cup in the first round.
Reeco Hackett-Fairchild earned the League One side a fourth-minute lead with his first goal for Pompey.
However, Scott Malone and George Saville hit back, while Callum Johnson was given a red card, as Gary Rowett’s side claimed victory.
And Cowley was full of admiration for the backing of the noisy travelling faithful as he get acquainted with supporters back in grounds.
He told The News: ‘They were brilliant, weren’t they. Wow, they were incredible.
‘It actually made me really proud singing “I’m forever blowing bubbles”. As a West Ham supporter I’ve waited for the day I’ve managed a team singing that!
‘At the end, did they know we lost? They were great.
‘I think they really appreciated the players’ efforts.
‘I will be honest, I’m not into vanity losses, but I thought the effort from the players was incredible and it was frustrating because we had such a good way into the game.
‘We made quite a few changes, probably more than Millwall, they were really strong, pretty flat out.
‘They are a good Championship side, really athletic, powerful and it’s a big jump between levels. I thought we acquitted ourselves really, really well.’
Pompey handed a debut to Shaun Williams, while Johnson and Hackett-Fairchild also earned starts in three changes to the team which won at Fleetwood.
There was also a surprise appearance from Michael Jacobs from the bench following the collapse of his Ipswich move.
And Cowley saw positives - and negatives - from the loss.
He added: ‘I’m just frustrated that we lost our way a little in the middle of the first half. Gass just got a little lost and sometimes that happens for young players.
‘But we found a way through that and came out the second half and, I thought, were in the ascendancy until the sending off.’
A message from the Editor, Mark Waldron
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