Ralph Hasenhuttl told Southampton midfielder Will Smallbone to keep his "head up" after his penalty miss proved crucial in the Carabao Cup defeat to Chelsea.
The Republic of Ireland U21 internatonal was introduced in the 77th minute at Stamford Bridge for his first senior outing in nine months having suffered anterior cruciate ligament damage back in January.
Within seconds of his arrival on the pitch, the 21-year-old had the chance to put Saints ahead but saw a header saved by Kepa Arrizabalaga before the fourth-round tie went to penalties, where Smallbone blazed over in the visitors' 4-3 shoot-out loss.
Hasenhuttl said: "We want to have a game where we are active, we show our supporters we are brave and very often you get the reward for it but today we didn't.
"Will could have been the hero because he had a big chance but for me the most important thing is he is back and fit again. It is great for him to be playing and he should take the positive things from this.
"Immediately he had a good chance and he was on the six and aggressive.
"After this long, long injury this is a positive thing he is back on the pitch. He shouldn't be too worried about the penalty. I have other players miss a penalty. He should have his head up and be positive over the next week in training."
Smallbone was in the Saints squad for the first time since the beginning of 2021 when he suffered his ACL injury during a 2-0 defeat against Leicester.
That appearance at the King Power Stadium had marked the Ireland U21's return following three months on the sidelines with a hamstring issue.
Reflecting on his cameo, Smallbone said on Twitter: "After 283 days it felt good to put the shirt back on again! Sorry about the penalty will come back stronger!! Thank you for your support."
The academy produced player was introduced in the centre of midfield with Southampton using wing-backs for the first time this season and Hasenhuttl was pleased with how his squad coped after they matched up Chelsea's own formation.
"It is something completely new," the Austrian admitted.
"We had no time to train it. Only yesterday one short session but in a way we see how tactically developed these guys are because they immediately know they can put it on the pitch. They did a good job against a top team."