During the first Test against New Zealand in late 2018, Mathews scored his ninth Test century. Mathews along with Kusal Mendis batted all over fourth day, which was the fifth time that Sri Lankan pair had done that in Test history. On fifth day, they put on an unbeaten double century partnership which overall lasts for 115 wicketless overs for New Zealanders. With rain interrupted, the match was ended in a draw. The partnership of 246, was also Sri Lanka's highest for any wicket against New Zealand and also Sri Lanka's highest in the second innings of a Test. It was the first time a Sri Lankan pair has added 200-plus runs in the second innings of a Test outside Asia.