After missing most of training camp and all four preseason games with a hamstring injury, Matthews made several critical plays to help the Packers win their regular-season opener at Philadelphia on Sunday.
A hit by Matthews ended up knocking Eagles quarterback Kevin Kolb out of the game. Then Matthews had a big hand in making sure Kolb's backup, Michael Vick, wasn't able to convert a critical fourth-and-1 play in the fourth quarter.
Still, Matthews left the game annoyed at himself about an interception he dropped.
"Trust me, that won't happen again," Matthews said after Sunday's game. "I'd give up a few sacks for that."
Matthews' two biggest plays of the game — a sack and the fourth-down stop — came on the Eagles' decisive final offensive series in the fourth quarter, a sign that his conditioning held up even with very little activity in training camp.
"Clay's a well-conditioned athlete," defensive coordinator Dom Capers said. "He's had the hamstring issue in both training camps, but probably a little bit of that is he does condition to the point where he really taxes his body because he pushes his body. He was playing, I think, at the same level at the end there. Your big players have to rise to the occasion."
Matthews had two sacks, seven tackles and a forced fumble against the Eagles, showing no sign that he spent most of training camp watching the rest of the team practice.
Well, almost no sign: he had just about enough of Vick's scrambling.
"I was gassed," Matthews said. "Anytime you have to chase Vick around, you're going to be tired. With four weeks off in camp and limited practice, it's going to be tough. But I made it through the game, I'll get some much-needed rest and take it into the Buffalo week."
Matthews said a few of his teammates ribbed him after his second-quarter hit ended up knocking Kolb out of the game with a concussion — because it meant they'd spend the rest of the day chasing Vick.
"Vick's an exceptional athlete," Matthews said. "He was moving around out there, making plays. I've been saying, the real story is, who's going to start for Philly next week?"
But Matthews got the best of Vick when it mattered the most.
With Philadelphia trailing by seven points and facing second-and-10 near midfield, Matthews sacked Vick for a 3-yard loss — succeeding where several of his teammates whiffed earlier in the half.
Vick completed a 12-yard pass on the next play, leaving them with fourth-and-1 on the Packers' 42-yard line.
The Eagles ran a sneak with Vick, Matthews shook off a blocking attempt by tight end Brent Celek, then got an arm around Vick as he tried to break through the line. He didn't make the first down.
"We expected them to run a quarterback sneak, and we prepare for this," Matthews said. "We go over everything from the last play to fourth-and-1 situations. Fortunately I was able to slip inside that tight end and knock a few guys off and create some mayhem back there. The game's on the line, you've got to make big plays. And fortunately me and some of the other guys can get him down and get off the field."
The pass rush was a significant question mark for the Packers going into this season. But they had five sacks on Sunday, getting pressure as Matthews frequently switched sides and ran stunts with defensive linemen.
"I was rushing a little bit from the right, a little bit from the left, saw a few eyes go, 'What's going on out here?'" Matthews said. "I don't know. I got a couple guard blocks on me that caught me right in the jaw, in the face a couple times, that's what I've come to expect. I think overall we got some good pressure on them."
The Packers escaped with a 27-20 victory in a tough road game, providing a boost to what already was a confident team.
"We know what we have, we know what we can do," Matthews said. "It's all about putting it together now."