Spurs winger Bale lit the blue touch paper ahead of Sunday's Wembley showdown when he declared his side would win because "we have the better team".
"We respect his opinion and we'll see on Sunday," Di Matteo said. "Obviously, I don't agree with him."
The sides drew both league matches this season, and Di Matteo added: "We played them twice in the league and both games were quite balanced in that sense.
"When you play a one-off game, it's difficult to say who's the favourite because of the form the team's in. The dynamic of the game is different."
Spurs have been above Chelsea virtually all season in the Barclays Premier League, but have thrown away what looked set to be a 10-point advantage over them a month and a half ago to lead their London rivals by just two points going into Sunday's showdown.
Di Matteo could be forgiven for holding back most of the players he planned to use in Wednesday night's Champions League semi-final first leg against Barcelona.
But he said: "I will look at the team for Sunday and only think about what's best for that game - to win that game."
On paper, Sunday's match is the least important of Chelsea's punishing end to the season, with qualification for the top four their top priority.
But asked whether he would sacrifice FA Cup glory for Champions League qualification, Di Matteo said simply: "I'd like both."
Source: PA
Source: PA