Mark Cooper insisted his Swindon team were under par and can improve despite a 3-1 win over Chesterfield.
Mark Cooper: Fortunate victory
Goals from Jack Stephens, John Swift and an 18th league goal of the season for Andy Williams sealed victory for Swindon.
But Cooper said: "The players won't be happy with that performance.
"We saw it through without too many scares but we didn't play particularly well.
"We played against a good team who came with a game plan to thwart us in the first half and come at us in the second.
"It nearly worked because they really asked us some questions in the second half. Fortunately, we managed to score our goals at the right times."
On-loan Southampton defender Stephens put Swindon ahead with a deft 17th minute header from Harry Toffolo's sweetly delivered free-kick but the lead lasted just three minutes.
Swindon's desire to play out from the back proved their undoing as skipper Nathan Thompson was caught in possession by Armand Gnanduillet and the ball was worked out to Sam Clucas who cut in from the right to curl in a left-foot shot around keeper Wes Foderingham.
The Robins restored the lead through a fine individual goal from impressive on-loan Chelsea midfielder Swift, who pivoted away from three defenders and finished from eight yards.
Chesterfield thought they had levelled when Jimmy Ryan's thumping volley crashed down off the underside of the bar, but the referee's assistant ruled the ball did not cross the line.
Swift played a key role as Swindon stretched their lead two minutes into the second half with a brilliant pass which sent Williams through to finish clinically.
Cooper added: " We needed the cushion of the third goal and it came at just the right time. This a young group of players but they keep passing tests.
"Nobody expected us to be where we are, so all credit to the players. We weren't as fluid as we can be but we'll take the win and move on."
Chesterfield boss Paul Cook admitted his side paid the price for poor defending but paid tribute to Swindon.
Cook's side had won five of their previous seven games but he said: "We conceded some poor goals.
"The referee helped them with one or two decisions but I'm being picky. Swindon are a really good side and I hope they go on to win promotion.
"We acquitted ourselves well in the second half but the game was gone by then.
"You can see why some teams come here and park the bus but we don't buy into that. We gave it a go and we're beaten by a good side who try and play the game the right way."