There were more than 1,400 Pompey fans packed into the sold out away end at Whaddon Road.
And Danny Cowley admitted that his side’s performance in a 1-0 defeat to Cheltenham let every one of them down.
There were certainly some bright moments in a frenetic first half that saw both teams have opportunities to break the deadlock.
But Liam Sercombe’s strike secured all three points for the Robins after the break and Cowley was dismayed by Pompey’s failure to deal with the danger.
The Blues boss said: “It’s incredibly disappointing and the second half performance was simply unacceptable.
“We had a good place at the break and had managed to turn Cheltenham over around 10 times in their own half.
“You know the first goal is going to be crucial here on a tight pitch and we couldn’t find it, while there was a penalty we didn’t get. There were clear-cut chances.
"I’ll be the first to pat them on the back when we play well and win, but I’ll also be the first to tell them when they’ve come up short."
“But we lacked a bit of quality to make the most of those moments and after the restart we were well short.
“They found momentum leading up to the goal and we showed no substance, character or tactical intelligence to overcome that. You could see what was coming.
“We’ve let everyone down and that’ not a nice feeling. It’s always a collective when we lose and there were some really poor displays.
“I’ll be the first to pat them on the back when we play well and win, but I’ll also be the first to tell them when they’ve come up short.
“We can understand the frustration from the supporters and we let them down with our performance.”
Cowley made five changes from the side that were unfortunate not to claim victory at Bolton earlier in the week.
He said: “The games are coming thick and fast, while we got home around 5am on Wednesday morning, so we needed to freshen things up.
“A few players were feeling stiff or carrying some muscle tightness, so we didn’t want to make a gamble.”