Town’s 4-2 victory at Rotherham United saw defender Max Clark replace the injured Darnell Johnson in the first half at the New York Stadium.
However, Clark was then withdrawn with 20 minutes remaining as Paddy Lane made his senior debut.
“I feel sorry for Max Clark,” Grayson said after watching his side make it seven points from the last nine.
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“Max came off the bench but we just felt with him getting booked, against a right wing-back who was lively, the best thing for the team was to take Max off because we didn’t want to be down to 10 men and give them the opportunity.
“It’s a really tough one on Max in the first place but Paddy came in and did the job we asked him to do.”
Johnson’s early departure capped a difficult few days for Grayson, who had already seen Anthony Pilkington and Harrison Holgate join Dan Batty on the absent list in the build-up to last weekend.
Nevertheless, one player’s disappointment can be another’s opportunity and those who figured did their coaching staff and the supporters proud.
Grayson admitted: “Competition for places is what it’s all about. The unity of the group when I need to make changes – whether it’s the starting part of the team or the substitutions – is you’ve got to make an impact.
“It’s not been great the last few days (with injuries) but you get on with it and other people get the opportunity.”
The win lifted Town into 17th place in League One going into a free midweek.
Attention now turns to the weekend when Grayson’s players face another promotion chaser with League One leaders Sunderland visiting Highbury.
Sunderland have won five of their first six but Grayson believes his players must take inspiration from their win at Rotherham.
“It should give the players a lot of confidence as individuals and collectively as a team,” he maintained.
“Rotherham are one of the best defensive teams.
“They have big centre-halves and wing-backs that can play as well – and we’ve asked questions of them.
“They don’t get much easier. We play Sunderland at home next week but it will be a buoyant team going into it full of confidence and we won’t be getting carried away with ourselves.”
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