Sri Lanka's Kusal Mendis (R) was unbeaten on 73 at lunch on Thursday in the opening Test against New Zealand

Christchurch (New Zealand) (AFP) - Kusal Mendis raced to 73 not out off just 51 balls as Sri Lanka made light of bowler-friendly conditions to reach 120-1 at lunch after being asked to bat on the opening day of the first Test against New Zealand.

Captain Dimuth Karunaratne was unbeaten on 33 off 62 balls after he lost the toss on a green-tinged Christchurch wicket and New Zealand captain Tim Southee opted to bowl.

Southee made the early breakthrough when he had Oshada Fernando caught down the legside for 13 in the seventh over, from arguably his worst delivery of the morning, to leave Sri Lanka 14-1.

But Mendis rode his luck to reach his 16th Test fifty off just 40 balls, despite the pitch favouring the bowlers and the floodlights on under overcast skies at Hagley Oval.

Mendis and Karunaratne had put on an unbroken 106-run partnership by the break.

The pair scored rapidly as a series of inside edges and top edges found the boundary, with Mendis hitting 15 of Sri Lanka’s 21 fours in the session.

Neil Wagner, in particular, came in for some harsh treatment, the quick bowler’s three overs costing 30 runs.

New Zealand’s new-ball pair Southee and Matt Henry did find movement through the air and off the pitch.

But their only success came when Fernando chased a ball that was swinging away down the leg side and sent an easy catch to wicketkeeper Tom Blundell.

Karunaratne survived a run-out scare on one when the throw at the stumps went wide and Mendis was given out lbw without scoring only to be saved by a review.

New Zealand made one change to the side that secured a famous one-run win over England last week with seam bowler Blair Tickner returning at the expense of batsman Will Young.