Opener Karunarate and Mathews came together in only the fifth over of the Sri Lanka innings after Tim Southee had taken three wickets — Sri Lanka was reduced to nine for 3 — with high-class swing bowling as New Zealand fielded after winning the toss.
The veteran pair had batted 23 overs by lunch, when Sri Lanka had recovered to 73-3, and continued throughout the second session before Karunaratne fell to a soft dismissal half an hour before tea when the tourists were 144.
Mathews batted on and was 71 not out at the break while captain Dinesh Chandimal was on 6.
The stand between Karunaratne and Mathews lasted 42.3 overs and was a classic example of technique and the value of perserverence in conditions which favored the bowling side. The ball was swinging, fractionally most of the time and substantially some of the time, and that demanded batsmen who stood tall and still at the crease and were able to make accurate judgements of line and length.
Karunaratne, continuing a strong run of form this year, had batted 200 minutes and faced 144 balls when he finally fell in unfortunate circumstances and against the run of play.
New Zealand had seemed to exhaust almost every idea for breaking the partnership until its third seamer, Neil Wagner, resorted to his successful tactic of recent seasons of bowling short and around the wicket.
Karunaratne had not been able to resist the pull shot, though there were two fielders back for the shot, and when he went to the shot once to often he misjudged the bounce and gloved a catch down leg to wicketkeeper B.J. Watling.
Mathews carried on and by tea had batted close to four hours.
Southee also resorted to short-pitched bowling after lunch, putting away the fuller length which allowed him to swing the ball and capture the early wickets of Danushka Gunathilaka (1), Dhananjaya de Silva (1) and Kusal Mendis (2) within the first four overs. As early cloud melted into a fine day and the ball aged, swing was less prevalent.