New England quarterback Matt Cassel — who will start his first NFL game on Sunday against the Jets — is focusing on blocking “the outside distractions” as he takes over for the injured Tom Brady.

The Providence Journal / Glenn Osmundson

FOXBORO — With each passing day, Matt Cassel has watched his life change.

On Sunday, after he led the New England Patriots to a 17-10 season-opening victory against Kansas City, his cell phone was flooded with text messages, more than 150, many from numbers he didn’t even know.

Usually, just his mother sends him a text after games.

On Monday, he led his first practice as the Patriots’ starting quarterback, taking the snaps usually reserved for Tom Brady.

Usually, he just gets a few as the backup.

Yesterday, another first: a crowd of at least 30 media members packed in front of his locker, waiting for 20 minutes before Cassel entered the fray, holding court on all things Pats and personal.

Usually, he chats with one or two reporters a week.

But for as much as things have changed for Cassel, he is determined for things to go on as usual.

“Once you get on the field, it’s business as usual,” he said when asked whether he feels any pressure. “It is more of the outside distractions: if you let it become a distraction, it will be a distraction. For me, it is just go and play ball as usual, try to have fun and realize it is a game. It’s a fun game and I have been doing it for a long time, so go out there and enjoy it.”

The atmosphere at the Meadowlands will most likely be turned up a few notches, as Jets fans formally welcome their own new quarterback, Brett Favre, to his new home. New York started the season on the road in Miami and Favre was able to lead the team to victory.

Cassel has famously spent the last eight years as a backup — first to Heisman Trophy winners Carson Palmer and Matt Leinart at USC, and then to Brady — but he looks at the experience in a positive light.

“It really hasn’t been that big of a struggle for me. It’s just about going in, getting your work done, and be ready when that opportunity comes. It’s here now,” he said. “Did I think it would take as long as it did? No. At the same time, I went and had a great education at USC. I had a great experience there. I came here and I’ve learned behind the best [Brady] the last four years. All in all, it’s not that bad.”

Being the second quarterback and having to be ready at a moment’s notice has its challenges, he said, but Cassel feels being the starter might be tougher: teammates look to you for guidance and want to see a top performance every week.

Much maligned for his play in the preseason, having not led the Patriots’ offense into the end zone while he was under center, Cassel said he wasn’t nervous that the coaching staff would choose Matt Gutierrez over himself as the backup quarterback.

Indeed, Gutierrez was released but brought back to the practice squad this week to serve as the No. 3 QB once again.

But because of Cassel’s inexperience — including last week’s action against the Chiefs, he is 35-for-52 for 405 yards, three touchdowns and two interceptions in his career, compared to Favre’s career numbers of 5,392-for-8,780 for 61,849 yards, 444 touchdowns and 288 interceptions — many who believed the Patriots were among the favorites to win the Super Bowl have downgraded the team’s chances significantly.

Cassel isn’t worried about the naysayers, using coach Bill Belichick’s favorite phrase to dismiss the dissenters.

“It is what it is. There are going to be a lot of people that make predictions on the outside and you can’t do anything to control it,” he said. “Nobody can foresee the future and nobody can say we are going to win 15 games or lose 15 games or do whatever. All we can do as a team is rally, gather together, work hard and go out there and put on a good performance on Sunday.”

The newly minted starter wants things to go on as usual, with one exception: thanks to the crush of media members and heat of camera lights he felt yesterday, he wants to install a fan in his locker to keep him cool during future chats.

smanza@projo.com