Oxford manager Chris Wilder praised his Crewe counterparts' style but made no apologies for his side's physical approach after their 1-1 draw.
James Constable grabbed United a share of the spoils before being sent off after Wilder's men conceded their first away goal of the season.
Oxford had gone 408 minutes without letting in a goal on their travels when David Artell headed in a first-half opener for Crewe.
But Constable levelled on the rebound after the break and then got his marching orders with three minutes to go to mark his 100th game in memorable fashion.
"Crewe are the best football side we have come across this season but they had another think coming if they expected us to come here and rollover," said Wilder.
"We might have upset a few people here. They have got the hump but I don't care. There was no way we going to be a soft touch."