The 33-year-old shot stopper has been discussing Celtic's upcoming clash.
The 33-year-old spent seven years at Hearts and feels the Scottish Premiership outfit gave a good account of themselves against the Hoops earlier this season.
That's despite Celtic winning 3-1, although that was at Parkhead and this will be a home game for Hearts.
The Bhoys haven't been in the best form of late, with boss Ronny Deila's exit at the end of the season also recently being announced.
And Gordon told the Celtic View: "It will be very tough. I thought they played some very good football at Celtic Park. They tried to pass it and they were taking free-kicks quickly and trying to play through the lines.
"They probably gave away goals at the wrong time as they were well in the game and they made it a very good game to watch."
Celtic are nine points above second-placed Aberdeen heading into the weekend clash.
Hearts, meanwhile, sit 17 points behind the Bhoys.
Celtic drew 1-1 with Ross County last week, where their performance was greeted with boos from the home fans, who also sent an unhappy message to the club's board.