Ange Postecoglou said Yves Bissouma “made a mistake” against Luton and hailed the way Tottenham responded to his red card.
Bissouma was sent off on the stroke of half-time at Kenilworth Road after being shown a second yellow card for a dive.
Micky van de Van secored a winner for 10-man Spurs in the second half as they went top of the Premier League with a 1-0 win.
Bissouma had already been hit with a one-match ban - which he will serve agianst Fulham after the international break - because his first yellow was his fifth booking of the season.
His second yellow card and subsequent red card means Bissouma goes back to a total of four yellow cards for the season, and the midfielder will be walking a disciplinary tightrope when he returns after his one-game ban.
Postecoglou said: “Biss made a mistake. He’s been brilliant for us. And it’s about how you react to it, and his team-mates made sure it didn’t cost us.
“I'm sure when Biss gets back in the team he will reciprocate and make sure that whatever else happens he can get us over the line. These things happen in football. It's disappointing. With all these things I always look at reactions. What are we doing about it? I thought the reaction was outstanding.”
Postecoglou added: "We showed a lot of character and resilience, which the team has showed a lot in the previous games before today.
“We started really well, should have been three or four up, but then you get the red card and it is a different type of game.
"I thought we held it together really well. They had some opportunities, we had a few of our own. In the end we get three points at a difficult place to go.
“It’s going alright, but we’re in October and still have a lot of work to do.”
