Indianapolis Colts quarterback Andrew Luck has hailed the performances of his side's defense this season.

The Colts have not allowed any one of their five opponents to score in the fourth quarter of their games in the current campaign.

"It is remarkable," Luck told reporters. "They've been incredibly opportunistic.

"It's so much nicer watching them instead of going up against them in training camp every day and you get frustrated when you throw an interception in a two-minute drill. It's been great."

The Colts are 4-1 in their season going into week six.