After losing to the Patriots 21-13 on Sunday, the Chargers definitely weren't happy about a key offensive pass interference call that went against them.

With the Chargers trailing 18-7 and facing a third-and-3 in the third quarter, Philip Rivers hit Travis Benjamin with a huge 41-yard touchdown pass that appeared to cut the lead to 18-13, pending the extra point. However, the Chargers didn't get any points on the play because the score was negated after Tyrell Williams was flagged for offensive pass interference.

On the play, officials explained that Williams was penalized because he picked the defender who was trying to cover Benjamin. The problem for the officiating crew is that the replay appeared to show that there was no interference.

Williams led his defender toward Benjamin's defender, but before there could be any type of pick, the Chargers receiver jumped out of the way, causing two Patriots defenders to run into each other, which created a clear path to the end zone for Benjamin.

In the top right corner of the picture below, you can see the two Patriots defenders run into each other as Williams ducks out of the way.

Tyrell Williams was called for OPI on a play where two Patriots players ran into each other. NFL/CBS

After the game, the Chargers were still irate about the penalty.

Wide receiver Keenan Allen told the Orange County Register that he thought it was a "Bulls--t call."

Chargers running back Melvin Gordon also thought the score should have stood.

"That was a clear-cut touchdown," Gordon said.

As for Rivers, the Chargers quarterback didn't rip the officiating crew, but he definitely thought there shouldn't have been a flag thrown on the play.

"I think that's going to be one that we're going to hear back from [the league office], to say that they weren't right," Rivers said. "But, too late."

Chargers coach Anthony Lynn was asked during his postgame press conference if he thought Williams interfered with a Patriots defender.

"I did not," Lynn said in a transcript provided by the team. "But, you know, I have to see the tape before I make that decision. You know, the referee called it, he saw what he saw. But I know we don't always, you know, go at that angle and then try get out the way, so that we don't pick. That's what we practice, but Tyrell said that's what he did. But I don't know, we will see. That was a big play of the game, I'll tell you that."

In the end, the Chargers didn't come away with any points on the drive because they had to punt one play later. If the touchdown had stood, it would've made things a one-score game with just 2:40 left in the third quarter. The Chargers did end up scoring a touchdown in the fourth quarter, but it was too little, too late.

This is the second time in three weeks that a controversial call has worked out in the Patriots favor. Back in Week 6, fans in New York were irate after a Jets touchdown was overturned in the second half of a game that New England would win 24-17.