Alex Samuel scored a last-minute winner as Partick Thistle beat Greenock Morton 2-1 at Cappielow to move to within five points of St Johnstone.
Cammy MacPherson gave the home side the lead in 22 minutes but Reuben Lopata-White was sent off for conceding a penalty and Ben Stanway scored from the spot.
Samuel struck at the end to earn Mark Wilson's men a crucial win ahead of next Friday's meeting with the leaders at Firhill.