FOXBOROUGH, Mass. (AP) -- The defending Super Bowl champion Patriots have lost Tom Brady's go-to receiver and their defensive leader to season-ending injuries.

Yet, as they entered the halfway point of their season following a defense-led 21-13 win over the Chargers on Sunday , they are showing the resolve of a team that's capable of making another run at the Lombardi Trophy.

Los Angeles (3-5) is again lamenting a missed opportunity against New England , but also likes how it's trending after a 0-4 start to 2017.

After losing two of its first four games, New England has won four straight games. It has been buoyed during that stretch mostly by a defense that will have to finish the season without captain Dont'a Hightower, who suffered a torn pectoral muscle in his shoulder in last week's win over Atlanta. That came after receiver Julian Edelman was lost in the preseason to a knee injury.

The defense is also making things work without cornerback Stephon Gilmore, an offseason pickup who has missed the past four games with concussion and ankle issues.

The Patriots (6-2) have given up just 51 points over their past four wins after allowing three of their first four opponents to score 30 or more.

"I think we're playing well with each other," linebacker Kyle Van Noy said. "We have a lot of new guys and a lot of young guys. It takes time to jell and that's kind of what happened is we're just trying to jell and get to know each other."

While the defense is figuring things out, the offense has regressed in recent weeks. It had just one touchdown Sunday and is averaging just 22 points over its past four games. That is down from 32 points per game over its first four games.

"We're not scoring as many points as we're capable of scoring, I know that," quarterback Tom Brady said. "I wish there was a simple answer to it, and the simple word would be execution. … I wish it would be better, but we're not. But we'll just keep after it."

Brady was 32 for 47 for 333 yards and a touchdown. He has 44 games with at least 300 passing yards and no interceptions. That is tied with New Orleans' Drew Brees for the most such games with a single team in NFL history.

Despite having their three-game win streak stopped, Chargers quarterback Philip Rivers also is hopeful as his team now heads into its bye.

"Something you can take from it is -- there's no participation trophies, but we're right there," he said. "We came to their place and we're right there."

HALFWAY THERE:Chargers coach Anthony Lynn likes to break the season into quarters, and it's not hard to see that his team was better in its second four games than in its first.

They have not been to the playoffs since 2013.

Since coach Bill Belichick's arrival, the Chargers have had five different coaches. New England is 8-3 against them during that stretch.

SPECIAL TEAMS WOES:If the Chargers are going to turn a corner in their final eight games, they must start with cleaning up their issues on special teams.

It was their biggest weakness against New England.

Travis Benjamin made a series of bad decisions on a punt return , leading to a safety that broke a 7-7 tie and set up the Patriots on a short field for a field goal. Los Angeles also missed a field goal, gave up a 71-yard kickoff return to Dion Lewis and botched a series of kickoff returns that repeatedly left them inside their 20.

"Last week, he made a play on a punt return to help us win the game. This week he made a bad decision," Lynn said. "That was a huge play in the game. You have to have some awareness of where you are on the football field. And he did not."

BOSA IS BOSS:Chargers defensive end Joey Bosa had a sack. Bosa has 19 sacks in 20 games, the most sacks by a player in his first 20 games to begin a career since the sack became an official stat in 1982.

FIRST-HALF PROWESS:Despite a pair of home losses, the Patriots are again one of the NFL's best teams as they reach the halfway point of the regular season.

New England is an NFL-best 97-38 in the first half of the season since Belichick's arrival in 2000.

The Patriots are off to a 6-2 start or better for the 16th time in team history and for the fifth straight season. They've won at least six games in the first half 11 times under Belichick.

BRADY VS. RIVERS:Brady is 7-0 against Rivers head-to-head, including two playoff games.

That's Brady's most wins without a loss against any opposing quarterback.

Rivers is just 1-7 against the Patriots (1-4 regular season). His lone victory came in San Diego during the 2008 regular season when Brady was out for the season with a knee injury.