"I don't think they've got other players of that ability," O'Connor told BBC Radio Stoke.
"They've got players coming in of a good standard but I'm hoping they'll miss him and that we can exploit that."
He continued: "By his standards he had quite a poor game against Spurs but he's a top-class player."
Chelsea are a point ahead of second-placed Manchester United in the Premier League table and Stoke have to play both sides before the end of the season.
O'Connor said: "We can get something from one of those two games. There's a belief within our squad that we can get something at Chelsea and therefore play a part in what's going to happen."
The Potters came within two minutes of beating Chelsea at Stamford Bridge in January 2009, having been ahead through a goal from Rory Delap until stoppage time, before going on to lose 2-1.
Terry scored one of the goals that knocked Stoke out of the FA Cup at the quarter-final stage in March.
Source: BBC Sport
Source: BBC Sport