Pradeep was confident - Mathews
Pradeep swayed away from a bouncer first ball - avoiding a reprise of his hit wicket from the first innings - then played and missed at a back-of-a-length delivery, and fended the third one away towards point.
Next ball - the penultimate delivery of the match - raised a raucous appeal from the hosts, and the batsman was given out by Paul Reiffel, only for the decision to be immediately reviewed. Replays showed Pradeep got a big inside edge, and lived on. The final delivery was edged to slip, but it only reached the fielder on the bounce.
"All Pradeep said to me was, 'Don't worry, I'm going to hold on. If they bowl short at me I'm just going to leave it'." Mathews said of his exchange with Sri Lanka's No. 11 before he went out to bat. "That was very encouraging from the tail-ender. I actually thought he did that exact thing. When they went for the lbw, we were not confident, because we couldn't see from behind. But he was pretty confident that he hit it, and thank God that he did."
Pradeep's lbw decision was the second piece of drama in the over after Rangana Herath gloved a short ball to the wicketkeeper - but his hand had already come off the bat handle. Herath did not wait for the umpire's decision to begin walking back to the pavilion.
"I guess Rangana wasn't aware of the rules," Mathews said. "It's a lesson learned. We all now know that if it hits your hand and it's off the bat you're not out."
Pradeep showed presence of mind to call for the review, even as England celebrated around him. "It wasn't the easiest time for Pradeep to go and bat, and to review the decision was also a brave effort. In that tense situation, your mind goes blank sometimes. It's always good to review it and luckily we used it. We hung in there."
Mathews was less enamoured by Sri Lanka's collapse either side of tea. The visitors had eight wickets in hand with 36 overs to play in the day, but lost three quickly to James Anderson's reverse swing, and were under immense pressure in the final session.
Mathews and Prasanna Jayawardene batted out 20 overs together, despite Jayawardene's severely bruised finger, before Rangana Herath faced 13 balls, until being dismissed.
"I thought we batted poorly after tea especially. The bowlers came and gave one last effort, and we fell for that. I thought Anderson bowled really well. Their seamers bowled hard and asked questions from our batters but we couldn't really handle it after tea. It shouldn't have got close.
"It was a great effort from our lower middle-order. Rangana Herath did well, and so did Prasanna, with a broken finger. He had had painkiller injections to keep going. It was a good effort in the end, but after tea we were too relaxed."
Alastair Cook faced some criticism for delaying his declaration, and Angelo Mathews said Sri Lanka were always unlikely to attempt chasing 390 on the final day.
"They could have declared earlier, maybe. Close to 400 runs to get on the last day is going to be a tough ask. The wicket was spinning a little bit, and it was playing up and down a little bit as well. We had to bat sensibly.
"We were going in a 50-50 mode. We wanted to bat till lunch, then tea, then see how we were. We were in a pretty bad situation after tea, and we couldn't do anything but go for the draw."
Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. @andrewffernando