Struggling Walsall remain in relegation danger following a home defeat by mid-table Tranmere.
The Saddlers are only three points clear of the League One drop-zone with three games remaining.
Andy Robinson's free-kick into the roof of the net was the difference between the two sides.
Walsall's best chance fell to Kevan Hurst, while they had Lee Beevers was sent off in the last minute for a second bookable offence.
VIEWS FROM THE DRESSING ROOM
Tranmere manager Ronnie Moore told BBC Radio Merseyside:
"It's difficult here because they've been on a tremendous run.
"To come here and win is a bonus for us.
"We said in the second half that if we want to get safe, let's go out and show some spirit and endeavour.
"I thought we dealt with nearly everything that came in and our goalkeeeper's done well for us late on when he's come for a couple of crosses."