Tranmere boss Les Parry was at a loss to explain his side`s uncharacteristically below-par performance in the 2-0 home defeat to relegated Swindon.
The Robins recorded only a third win of the year, taking a 10th-minute lead with their first chance when Jean-Francois Lecsinel netted from close range following a Michael Rose corner.
Michael Timlin then extended the lead after 38 minutes with a fine 25-yard strike after a long clearance
"We were just not at the races and it is hard to pinpoint why," said Parry. "We are a bit prone to losing to teams that are below us. I was terribly disappointed. It was a game we certainly should have won.
"There were a few turning points. Had we taken our chances it might have been very different. We missed a tap-in and we hit a post with an excellent free-kick.
"But we were so, so sloppy at times. It just did not feel right. It was a poor performance and we have go to take it on the chin. Swindon certainly raised their game and we did not answer them."