Sri Lanka will be expecting to win - they won the group match against New Zealand in Mumbai and the home advantage could be the difference.
The Black Caps will know that if they bat first, a score of around 220-230 will not be good enough.
John Wright, the coach, has already mentioned that he wants his batsmen to read the game and after 35 overs have seven wickets in hand to push for a large total.
The problem is that they will face a menacing spin attack which difficult to read. The other problem is that the batsmen have difficulty in working the ball for singles.
Sri Lanka have in-form players - Dilshan (2), Tharanga (2), Sangakkara and Jayawardene (one each).
The Black Cap bowlers need to deny them big scores with accurate bowling and sensational fielding.
For New Zealand, Brendon McCullum and Taylor have one century each although Ryder is finding form and Guptill is good enough to make his mark.
Watch out for Oram, he is due to explode. Southee is the leading wicket-taker for both teams with 15 wickets, but Malinga, Muralitharan, Mendis and Rangana Herath might have the last say.