Paul Hart set his sights on five unlikely wins to save Swindon after a 1-0 defeat at Exeter.
Ryan Harley hit a late penalty to give the Grecians victory and leave Swindon seven points adrift of safety with seven games remaining.
Hart said: "I am disappointed in the result and disappointed in the performance. That is the worst we have played since I have been here and that was disappointing because we have prided ourselves on improving performances over the last few weeks. It would have been good to have taken something from the game, but we have said all along we need five wins and that is what we still need."
He added: "We weren't at our best and I have no complaints with the penalty, there was a handball and generally, if you handball it in the box, you get a penalty given against you. I'm not sure whether our performance on Saturday took it out of us. It was a big game and we played exceptionally well at Brighton. Whether that has taken its toll, I don't know.
"It is a two hour drive down here, but I thought we started off really well. We were excellent for the first 20 minutes, but we couldn't maintain it. The players are all very disappointed with the result.
"Perhaps we should have settled for a 0-0, it was only a penalty that did us.
Exeter boss Paul Tisdale said: "I am satisfied with three points and we needed it. We have had a couple of losses and the result was everything. We got it and I am really pleased.
"I didn't see anything of the penalty if I am honest. I can only trust the referee's decision. I hear it was a handball, but whether it was lucky or deserved, I don't know.
"It was very foggy and it happened a long way away. The referee blew his whistle and that is all that matters. It took us some time to find some tenacity with our performance."
He added: "It takes us past 50 points for the season and past our total for last season, so that is good and progress on last season. Again, it shows the club is making progress."
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