Bill Belichick says his New England Patriots side have "a lot of work to do" ahead of the 2018 NFL season following a 25-14 loss to the Carolina Panthers on Friday.
The veteran coach struggled to find any positives from the game in Carolina, as last term's runners-up suffered their first loss of preseason.
In a post-game news conference, Belichick said: "The Panthers obviously did a very good job. Coach [Ron] Rivera and his staff and their team played well in all three phases of the game and outplayed us across the board for four quarters.
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"So we've got a lot of work to do. There really wasn't any part of the game that was competitive, so we just have to go back to work and see if we can find a way to do things better than we did tonight. Sorry, but that's all there is to say.
"We weren't able to accomplish much, didn't play well in any three phases of the game, so [we've] just got to get back to work and do a better job than that."
Quarterback Tom Brady, who went 12 out of 18 for 108 yards in the first half, added: "I think it's a lot of execution that we need to certainly get better at in the next couple of weeks because we play next week and after that, they all count.
"If you want to put them in the win column you've got to go and earn that and we certainly didn't play that way tonight. Our execution wasn't good enough to score enough points.
"Our execution needs to be better. I mean, you look back at a lot of the things and I thought about them the whole second half, all the things that we could do. And it's a lot of us. It's not so much what the other team's doing, although you know, it's a very good defense, it's our base execution that needs to be better."