When the Chargers have the ball

A lot will depend on the health of QB Philip Rivers (17) and RB LaDainian Tomlinson (21). Both injured knees against Indianapolis and, while both say they expect to play, no one's sure what San Diego will get from them. TE Antonio Gates (85), with Tomlinson the Chargers' most important offensive weapon, will also be less than 100 percent after playing last week with a dislocated toe.

Tomlinson, the NFL's MVP last season, can more easily be replaced by the combination of Michael Turner (33), one of the best backup running backs around, and the explosive Darren Sproles (43), who scored last week in the 28-24 upset over the Colts on a 56-yard screen pass.

San Diego has also gotten a big lift from the development of WR Vincent Jackson (83), who combines with Chris Chambers (89) in a very athletic wide receiving corps. If Gates isn't 100 percent, the 6-foot-5, 245-pound Jackson provides a tight-end like target. If Rivers doesn't go, Billy Volek (7) is an experienced backup in his eighth season who engineered the winning TD drive in Indy.

The Chargers could have success in the air, especially if Rivers can play. Jacksonville's David Garrard found holes in the New England secondary, especially to the outside, in last week's 31-20 Patriots win. Jackson and Gates are big enough to go over the relatively small defenders, all but ex-Charger Rodney Harrison (37), the strong safety, under 6 feet. Still, CB Asante Samuel (22) was an All-Pro this season with six interceptions, and Harrison, a former Charger, is one of the most aggressive and experienced safeties in the league.

Rivers was protected very well by the Chargers' offensive line, led by LT Marcus McNeill (73) and LG Kris Dielman (68). But he's not mobile when he's healthy and will be hampered even more by his knee problem. Look for more blitzes than usual from New England's 3-4 defense, especially from OLBs Mike Vrabel (50) and Adalius Thomas (96). DE Richard Seymour (93) has been one of the game's best DLs this decade but missed the first half of the season with a knee injury. Ty Warren (94) is an effective two-way DE and DT Vince Wilfork a premier run-stopper. The inside LBs, ex-Charger Junior Seau (55) and Tedy Bruschi (54), are well into their 30s, but use their experience well.

When the Patriots have the ball

It all starts with NFL MVP Tom Brady (16), who set a league record for touchdown passes with 50 throwing to Randy Moss (84), who set a record with 23 TD catches. If the defense double and triple-teams Moss, as Jacksonville did in limiting him to one catch last week, there is Wes Welker (83), Jabar Gaffney (10), Donte' Stallworth (18) and TE Benjamin Watson (84), who had two TD catches last week against the Jaguars. The 5-foot-7 Welker tied for the league lead with 109 catches and is almost impossible to cover underneath when Moss is blanketed deep. Add in Kevin Faulk (33) as the pass-catching running back and Laurence Maroney (39), who rushed for 122 yards last week against the Jaguars, and it adds up to a record 589 points in the regular season, or almost 37 a game.

What makes the Patriots offense even harder is that Brady has a quick release and the offensive line, led by LT Matt Light (72), LG Logan Mankins (70), and C Dan Koppen (67) protects him extremely well, allowing just 21 sacks this season.

They will be under pressure this week from a San Diego defense that leads the NFL with a plus-24 turnover ratio and got two interceptions off Peyton Manning in the 28-24 win over Indianapolis last week. Antonio Cromartie (31) led the NFL with 10 regular-season interceptions and had another in the playoff win in Indianapolis last week. Linebackers Shawne Merriman (56) and Shaun Phillips (95) led the team with 12½ and 8½ sacks respectively. They are the keys to the 3-4 unit that is anchored by NT Jamal Williams (76) and ends Igor Olshansky (99) and Luis Castillo (93), with ILB Stephen Cooper (54) getting double digits in tackles in 15 of the 18 games.

The defense has been one of the main reasons for an eight-game winning streak. After a 5-5 start learning new schemes, the Chargers have turned it around under coach Norv Turner and defensive coordinator Ted Cottrell. In those eight wins, the Chargers have allowed 13.1 points a game compared to 21 during their 5-5 start.

Special teams

Ellis Hobbs (27), a starting cornerback, had a 108-yard kickoff return for a touchdown on opening day against the Jets. But for the most part, New England's special teams are more about playing it safe than breaking big runs. Welker (83) handles most of the punt returns and averaged 10 yards per return although he is most treasured for having good hands.

Punter Chris Hanson (6) was underworked, a reflection of New England's offense. In half of the 16 regular-season games, he punted two or fewer times. Kicker Stephen Gostkowski (3) replaced Adam Vinatieri when the league's best clutch kicker was allowed to leave as a free agent at the start of the 2006 season. Gostkowski wasn't asked to win a game this season. And while he missed one last week against Jacksonville, he was 21-of-24 in the regular season for New England.

The Chargers' Nate Kaeding (5) was 24-of-27 during the regular season this year. As a rookie in 2004, he missed a field goal that could have won a playoff game against the New York Jets.

Sproles has been a major weapon on special teams for the Chargers, returning both a punt and a kickoff for a touchdown in a regular-season win over the Colts. He has forced teams to kick away from him, a threat that allows the Chargers good field position.

Coaching

The matchup between Turner and New England's Bill Belichick looks on paper to be a mismatch.

Belichick is the best coach this century, having won Super Bowls after the 2001, 2003 and 2004 seasons and led the Patriots to the first 16-0 regular season in NFL history this season.

Turner, one of the best offensive coordinators of the past two decades, was in a no-win situation when he was hired to succeed Marty Schottenheimer when the Chargers lost their first playoff game to the Patriots after going 14-2 in the regular season last year.

He never had as much success during head coaching stints in Washington and Oakland. His 11-5 regular-season record this season was his best, but his overall career record is still well under .500 — 69-87. However, he is 3-1 in playoff games, two of the wins this season over Tennessee and last week's upset against defending champion Indianapolis.

The Chargers' 5-5 start also put heat on Cottrell, who took over for Wade Phillips after he was named the coach in Dallas.

Intangibles

The biggest intangible for Sunday's game will be the weather. The long-range forecast is for temperatures in the 20s with high winds. That could make it a running game, which could favor San Diego if Tomlinson is healthy.

It also would turn it into a field-position game, something the Patriots aren't used to in a season in which they have tended to cruise up and down the field. So it's possible the warm-weather team will get an edge in cold weather.