The FC Twente boss was pleased with his team's performance on Thursday night, and has turned his attention to the next league fixture
After conceding a goal on the stroke of half time, Twente returned to the field a different side after the break, and went 3-1 ahead before the hour mark had passed.
McClaren spoke of anger in the dressing room, after Twente let their well-deserved lead slip.
"They were furious about the goal, one minute earlier. That aggression was transformed into positive energy. That's why we won," claimed coach McClaren, speaking to Ad.nl.
"I knew they could do it. From the beginning we played offensively and aggressively. This led to many chances. Even in the first half.
"At 3-1 it was tactically a bit tricky. We decided to go for it because we were playing well," explained McClaren.
"We wanted the group stage of the Europa League. It is important for the players to play at international level."
However, the English boss warned against complacency and called for focus ahead of their continued Eredivisie fixtures.
"The road of qualifications was long. Now we can enjoy it, but we quickly have to get both feet on the ground. Sunday we face VVV," stated Twente's boss.