Still stinging from a 31-24 home loss to the Seattle Seahawks, the New England Patriots travel across the country to face the woeful San Francisco 49ers on Sunday.

And they will do so without Rob Gronkowski.

The big tight end, injured by a smashing hit from Seattle's Earl Thomas on Sunday night, missed five plays but came back and finished the game, which ended when an attempted fade to him in the end zone was incomplete. He was ruled out of the game against the 49ers on Friday.

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On Monday a report surfaced he suffered a punctured lung. Then Tuesday another report said it was a bruised sternum.

There was no Gronkowski news Wednesday -- except that his brother, Glenn, was re-signed to the practice squad.

While all was quiet on that front, it was apparent neither Gronkowski will be on the field when the 7-2 Patriots visit the 1-8 (with eight straight losses) 49ers.

Clearly, Rob Gronkowski's absence makes the powerful New England offense weaker. But the injury took focus away from what the Patriots defense did Sunday, which was little as Russell Wilson threw for 348 yards and three touchdowns.

Chip Kelly is the coach of the 49ers now, but last year he brought the Philadelphia Eagles to Gillette Stadium and won, scoring 35 points.

"(Coach Bill Belichick) has been on us about that game, too," defensive captain Devin McCourty said Wednesday. "Obviously, we didn't do some things well that game, so we just talked about the importance of, with Chip Kelly being there now, they'll definitely probably go through that game, and things that they gave us trouble with they'll look at and probably go back to.

"He's (Belichick) trained us as players I think in really all phases of the game about being prepared for those things, so we've gone through that game a little bit, just watching and seeing how we might get attacked, obviously, not by Philly but by a team coached by Chip Kelly."

Asked what his team has to do to calm the fears of anxious Patriots fans about the defense, McCourty said, "It's simple. We've just got to play better -- there's nothing I can say to calm that or anything, we've just got to go out there and play better. I think that's what everyone in the locker room and everyone on the defense wants to go out there and do. There's nothing to say. You've just got to go do it."

The 49ers are 29th in the NFL in total offense and 30th in passing. But they're seventh in rushing, with Colin Kaepernick always a threat to take off with the football. And the New England defensive players have been impressed with the way the Niners have moved the ball the last two games -- the third and fourth games with Kaepernick as the starter.

"I mean, if we'd have played well (last week) we'd still have something to prove," New England defensive end Chris Long said. "Every week we have something to prove. If you have a mindset any different in this league, you're going to get embarrassed because there's good teams every week that you have to play that has weapons. San Francisco certainly has that."

The 49ers' only win was a 28-0 opening victory over the Los Angeles Rams, who also remain on New England's schedule. They lost by three points at Arizona last Sunday.

Earlier this week, Kelly, the former offensive coordinator at the University of New Hampshire, revealed some extremely important news on his relationship with Belichick.

"We're Facebook friends," Kelly said. "We spend a lot of time online together.

"He is a good friend. He's always been very, very kind to me, whether I was at New Hampshire or Oregon or now, when I've been in the NFL. Very good friend. ... I was just very thankful that he is a friend of mine, and I've got great respect for him. Excited about the matchup this week and getting a chance to coach against him again."

Talking about Kaepernick and the Niners' attack Wednesday, Belichick said, "They run the ball as much as any team in the league so that sets up their play action and some of the quarterback movement plays that he's good at, as well as their third-down package. He has a good group of skill players to work with. The receivers are good, the tight ends are good, the backs are very good. They can move the ball."