ALAMEDA, Calif. -- So what if Donald Penn is in his 11th NFL season? The Oakland Raiders' Pro Bowl left tackle, whose holdout lasted through training camp and two preseason games, still gets a case of the nerves.

Especially with how little actual football work he got before the season opener against the Tennessee Titans.

"I'm not going to lie to you guys," Penn told reporters this week, "but I was worried going into that dang game. I played a couple plays in that Dallas [preseason] game and then, in practice, I was pushing myself extra hard, [more] than I usually do, just trying to get ready. Because I really didn't know."

Penn said the Raiders' staff had a plan in place to rotate at left tackle should he have needed a rest. Instead, he played all 66 snaps.

"I got an IV before the game, something I usually don't do, just to be proactive. And then, once the [game] started flowing, I was surprised," Penn said. "I was surprised in myself with how good of shape I was in and how I went through that game."

Penn, who thanked his trainers at Proactive Sports Performance in Los Angeles for keeping him in shape during his holdout, was charged with allowing just one quarterback pressure, per NBC Sports Bay Area. And one missed assignment still led to a highlight play -- running back Marshawn Lynch absolutely trucking Titans defensive tackle Jurrell Casey.

"First of all, I missed the damn block to make Casey free, because I made an adjustment but I forgot to tell K.O. [left guard Kelechi Osemele] the adjustment," said Penn, who said he planned to "slow-play" to help tight end Clive Walford but did not tell Osemele.

"I wish I could have that play back but, man, [Lynch] made that thing work," Penn said with a laugh. "I saw that thing right there; I heard the impact, and I picked up Marshawn [and] I said, ‘You're done. Just go to the sideline. We don't need no more from you. You're done.'

"That's what Marshawn does. We're not supposed to leave anyone unblocked, but that one time I did. He ran right through him and got those extra yards we needed."

Raiders coach Jack Del Rio acknowledged he would have rather seen Casey blocked, but he also said Penn's experience helped in other facets.

"Donald has over a decade of experience starting," Del Rio said. "He's been in our system. This is his third year now in our system, so it's a lot different than a guy coming in as a rookie and missing so much camp."

And while Penn reported to the Raiders without a desired new deal -- he is in the final year of a two-year, $11.9 million contract scheduled to pay him $5.8 million this season -- reports have swirled this week that an extension could be in the works.

Penn, 34, said he has room to improve, what with the Raiders' home opener against the New York Jets on Sunday (4:05 p.m ET, CBS).

"You know me, man, I'm hard on myself, so I've got a lot of stuff I've got to fix," Penn said. "One bad play, man, I missed my hand swipe and dude knocked me on my back real bad. That's one play.

"Timing-wise and getting my hands in a certain place ... but I was happy with myself with how I played because they're a good front."