The veteran played brilliantly for 88 but fell victim to Moeen Ali shorly after tea to tilt the match back in the tourists' favour. Dilruwan Perera then went with the final ball of the day as rain arrived to curtail play and leave the match on a knife-edge, a knife-edge that Mathews felt was entirely avoidable.
"It is evenly poised," he said.
"It is very unfortunate I got out at a very crucial time. But we still have got a batter at the crease. Then guys like Akila Dananjaya and Suranga Lakmal are no mugs with the bat. So we are not out of the game.
"If we get one good partnership we are in with a win."
On a pitch that was helpful to the spinners but at other times seemed to slow up and help the batsmen, Mathews judged the track better than any of his teammates as he steadied the ship after Jack Leach's devastating spell of wickets in the morning.
"It was one of those wickets where you can get a good ball any given time.
"You have to look to score runs all the time and one good ball will come your way. You will definitely nick it or you will get out. It is a wicket where there is lot of assistance to the spinners.
"Credit to England for bowling so well. They didn’t give too many loose balls. We had to work extremely hard to score runs. Dimuth [Karunaratne] was superb today with the bat and it was extremely unfortunate that he had to fall for a brilliant catch. That changed the game. He was the batsman in form. Had we got a bigger partnership we would have been in a commanding position."
The catch that did for the dangerous Karunaratne was an inspired piece of work by Keaton Jennings, who had earlier taken a sharp one-handed effort to dismiss Kaushal de Silva.
Jennings pre-empted Karunaratne's paddle sweep and got moving from his short leg position, jabbing a hand at the ball and failing to hold on - only for the ball to loop to wicketkeeper Ben Foakes and break a crucial partnership.
"You kinda see the shape of the shot," said Jennings afterwards.
"Foakesy was coming around to try and cover if he went fine. I’ve covered it and he got a bit more wood on it and I parried it straight to him.
"When you look at a lot of the other sweep shots that the guys play, you’ll see us both running. But I suppose that one just ends up at one of us and thankfully it stayed off the ground."
While England's wickets after tea have left Sri Lanka with a difficult task of 75 to win with just three wickets remaining, Mathew retains hope that the mercurial Niroshan Dickwella can steer his side to what at times seemed an unlikely victory.
"Had I put up another partnership with Dickwella it would have been a different story. But we are still in the game and we are in with a chance."
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