FOXBOROUGH, Mass. — After 56 years in San Diego, the Chargers packed up and made the 120-mile trip north up I-5 to Los Angeles prior to the 2017 season.

They held training camp in a facility that wasn’t completed, called a 27,000-seat, soccer-specific stadium home, had a fan base smaller than a tapas plate, and a first-year coach in Anthony Lynn. Not your typical recipe for success.

The early results were predictable as the Chargers started 0-4. But their effort and intensity, with three of the losses by three points or less, proved to be a precursor of good things to come.

“I don’t want to make more it than it is,” quarterback Philip Rivers said Wednesday during a conference call, “but I certainly do think it has weathered us and contributed to our toughness and resilience and all those adjectives I could give you.”

When the second-seeded Patriots meet the No. 5 Chargers at 1 p.m. Sunday in an AFC divisional-round playoff game at Gillette Stadium they’ll be taking on a team that is mentally and physically up to the challenge.

Southern California laidback these Chargers are not.

The Chargers won nine of their final 12 games last season _ one of the losses was here to the Patriots _ and lost out on a playoff berth on tiebreakers. The good times continued this season as they went 12-4 to earn their first postseason invite since 2013.

The Chargers upset the Ravens in the wild-card round last weekend to improve to 22-7 since that 0-4 start.

“Relocating a franchise is not an easy thing to do,” coach Bill Belichick said. “Dealing with all of that, all of the other challenges that normal teams have in the National Football League are difficult. But then you throw relocation and international games and some other things that have come up along the way on top of that.

“I think that that organization has shown a lot of resiliency, mental toughness and certainly a very high level of performance over a sustained period of time since they were 0-4.”

That’s been especially true on the road.

The Chargers improved to 8-1 (.888) on the road with their win at Baltimore. They also won a “home” game at London

For comparison sake, the rest of the league went 94-152-2 (.384) on the road before going 3-1 in the wild-card round.

“I think it says a lot about the mental toughness of their football team,” special teams captain Matthew Slater said. “To be able to go on the road, hostile environments, essentially playing a game at 10 a.m. West Coast time this past weekend and being ready to go.”

The Chargers traveled nearly 31,000 miles during the regular season, which was the second-highest total in the league. The cross-country trips to Baltimore and New England will tack on another 10,000.

It’s a group that has shown a willingness to go the distance in search of the franchise’s second Super Bowl berth _ the first came in 1994 _ and first Lombardi Trophy.

“We’ve had some tough road trips,” Rivers said. “We’ve gone across country and had a home game in London and been all over. It’s a tough group, it’s a tough team.

“We’re well aware the Patriots haven’t lost at home and we haven’t lost outside of LA County, so one of those streaks is going to be broken Sunday.”

The Patriots were the only team to go 8-0 at home this season while the Chargers’ lone road loss was to the Rams at LA Memorial Coliseum.

The Chargers’ road wins have been doubly impressive because they’ve not only come against some very stiff competition, but in some of the league’s toughest venues. In addition to Baltimore, they were victorious at Denver, Kansas City, Pittsburgh, and Seattle.

“We have a tough football, no doubt _ I believe that,” Lynn said. “I think going on the road doesn’t really faze this team. We just love ball. We like playing football and competing.

“We know going into Foxboro they’re undefeated and they’re tough to beat, period. It doesn’t matter where you play the Patriots, they’re tough to beat.”