Mendis suffered an injury on his right knee while Jayasuriya has sustained an injury above the knee on his right leg after the duo collided near the boundary rope in the final over of New Zealand's chase on Tuesday in Pallekele. Mendis was sent for an MRI scan on Wednesday and the reports are expected later in the day.
Colin Grandhomme and Tom Bruce helped New Zealand chase down an imposing 162 run target set by the Lankans to win the 2nd T20I and seal the 3-match series 2-0, with the third game to be played on Friday (September 6) at the same venue.
Sri Lanka have opted against any replacements for the injured players.