The Peruvian midfielder was sent off after just 11 minutes in the 1-1 draw at Fratton Park last night for apparently elbowing Richard Hughes.
O'Leary, however, disputes that the offence was violent and will makehis view clear to the Football Association disciplinary committee. In the light of recent events he may have a chance, as three of six previous dismissals this have been after been rescinded after video analysis.
West Ham's Paul Konchesky, Sunderland's Andy Welsh and Newcastle's Jermaine Jenas have all been let off suspensions after being dismissed. But this time O'Leary is taking on one of the most eagle-eyed officials in the business in the referee, Graham Poll.
O'Leary said: "It is only a hope although I will definitely be appealing [for wrongful dismissal].
"The referee has interpreted the offence as violent conduct. The difference in the other cases which were overturned is that they [the referees] admitted they made mistakes.
"I thought this was a joke. Nobby Solano a violent player? Give me a break. He's had his shirt ripped off on the way through. Nobby tried to brush the fellow away.
"The bans that have been rescinded have been right. Hopefully, ours will be the same. He's not even hit him, but we had to do without an influential player for 80 minutes."
O'Leary, who has added to his ranks by finally securing the signature of the striker Milan Baros from Liverpool for £6.5m and may give the Czech his debut at home to Blackburn on Saturday, will get no support from Portsmouth's manager, Alain Perrin.
The Frenchman said: "Hughesy deserved a yellow card. He was pulling the player's shirt but then he was hit with an elbow and for me the sending off was a normal decision. Sure, he [O'Leary] disagrees but maybe that is because the red card has happened to his team."
Villa overcame the loss of Solano by immediately taking the lead through Hughes' own goal from the subsequent free-kick, but Lomano LuaLua's superb goal before half-time earned a point for Pompey.
Neither Villa nor Pompey have won a Premiership match since April but while Perrin has struggled to add top quality to a new-look side, O'Leary is gradually boosting his armoury.
He said: "We are a good unit already and we will do well this season. I don't worry about the stats from last season when we finished against good sides like Bolton, Spurs and Liverpool in the last few weeks."
The Irishman has already signed Aaron Hughes from Newcastle, Kevin Phillips from Southampton, Patrik Berger from Pompey and now Baros and the chairman, Doug Ellis, has promised him more money, with £5m earmarked for another central defender.
"I'm absolutely delighted," he said. "I think we need that. I hope we can get some more quality players. I'd like to get two more in.
"I think Baros is a team player and I think he'll score goals. Hopefully I'll get one in at least and it'll make us stronger."
O'Leary denies he has had offers for Solano, who suffered his second sending-off in Villa colours after being dismissed against Middlesbrough in April last year.
O'Leary said: "He came to see me saying, 'What is all this?'. His agents said they had been aware of interest [from Liverpool] but nobody made me aware.
"I wouldn't want to sell him. He's a quality player and we certainly missed him on Tuesday night.
Solano will face a three-match ban unless his appeal is upheld, but O'Leary has Berger available after a thigh injury for Blackburn.
He said: "I think he will make the bench although he had no chance to play against Portsmouth which he would like to have done."
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