Give the depleted San Diego Chargers a lot of credit for staying with New England, but the lesson here is pretty basic: You don’t beat touchdowns with field goals (although the Giants did it in the 1990 NFC championship game when they beat the 49ers, 15-14).

Playing without LaDainian Tomlinson and with Philip Rivers and Antonio Gates both hobbling, the Chargers needed some breaks on offense but, instead, their poor performance in the red zone did them in.

San Diego’s defense played enough to win the game. The big difference between the teams was a 24-yard touchdown drive following a New England interception.

The Chargers seemed to play too conservatively on offense. Perhaps the strategy was due to the injuries. But San Diego was not going to beat New England this way.

Then there’s the way the game ended, and this is not a second guess. I said it before it happened, when the Chargers, trailing by the eventual final score of 21-12, punted from the Patriots’ 36-yard line with 9:13 to go.

At this point, San Diego needed two scores including at least one touchdown. The Chargers needed to be aggressive and instead they were passive. They played right into the Patriots’ hands, and the punt was essentially a give-up play, designed to keep it close.

Well, it kept it close. But the Patriots ran out the rest of the time on a 15-play, 65-yard drive that ended with two kneeldowns.

The difference in the game: San Diego got inside the New England 10-yard line three times, including two first-and-goal situations, and couldn’t score a touchdown, and one of Rivers’ two interceptions set the Patriots up at the Chargers’ 24-yard line for an easy touchdown.

What would have happened were the Chargers healthy? We’ll never know. We do know the Patriots are one victory away from a 19-0 season. We also know they are not unbeatable. Just unbeaten.

The day’s upset, of course, took place in the NFC game. The Giants are a terrific story, a team that seemingly found itself in a loss – the season-ender against the Patriots.

Remember all the talk before the game – Tom Coughlin should play the regulars, not play the regulars, he didn’t need the game, he needed to try to prevent the undefeated season, he needed to get his own team ready for the playoffs, and so forth.

Coughlin and his team didn’t want to be No. 16 on a 16-0 record by the Patriots. It turned out that they were, but Eli Manning was magnificent that night and has played very well ever since. The close call against New England seemed to bring the Giants together. I spoke with Archie Manning, Eli’s dad, after the Giants beat the Packers, and Archie agreed. “I don’t know how you measure it, but it gave them a boost,” he said.

During the regular season, Eli shared the NFL lead with 20 interceptions. He has gone through three playoff games now without losing a turnover.

The Giants hardly looked like a Super Bowl team at the start of the season. They were 0-2 and down by 14 points at halftime in their third game. But something clicked. Then they were up and down most of the year. They are the third NFL team to win three road games in the playoffs, but the first to do it in the NFC which usually goes more according to form than the AFC.

For more on the NFC game, read my take at www.nfl.com.