Rangers missed a golden opportunity to claim only their second away win of the season when they failed to trouble a stand-in keeper over 70 minutes.
Iain Dowie was happy enough with the 0-0 draw at Swansea's Liberty Stadium on Tuesday night, but admitted he was disappointed with the performance.
Skipper Martin Rowlands was involved in the game's flashpoint when he collided with Swans keeper Dorus De Vries, but Dowie exonerated the midfielder from blame.
The Swans had no goalkeeper on the bench and were forced to use defender Alan tate between the sticks for the remaining 70 minutes of the match.
But the Rs failed to capitalise on their good fortune as the home side made the better chances and worked hard to deny the visitors possession.
"We pride ourselves on our ball retention, but that didn't happen tonight," Dowie said. "They've had an outfield player playing in goal and we haven't tested him at all and that is not good enough."