Clearly, the phrase “must win” has earned a place on the all-time list of sports cliches, but that’s where the Bills are come Sunday afternoon at Hard Rock Stadium in Miami Gardens.

Buffalo (6-3) visits the Dolphins (1 o’clock CBS-TV, 95.7 FM, 100.1 FM, 550 AM) under plenty of pressure.

The Bills, in the first half of the season, went 6-2, winning every game they should have. Home losses to defending Super Bowl champion New England and Philadelphia, which won the Lombardi Trophy the year before, were predictable.

To many Buffalo fans, last Sunday’s 19-16 loss at Cleveland was the first defeat in the “shoulda won” category. But, even though the Browns came in at 2-6, they were a field goal-favorite in the eyes of the bettors.

TOMORROW, on the road, the Bills are giving 6 ½ points to a team they barely beat at New Era Field a month ago. Miami (2-7) has won its last two — home with the Jets, at Indianapolis — and played well in its last five games including a 17-16 loss to Washington when a potential game-winning 2-point conversion failed on its last possession.

A week after, the Dolphins fell to the Bills, 31-21, but led in the fourth quarter and it was a 3-point game with barely 90 seconds to play until safety Micah Hyde returned an onside kick for the clinching touchdown.

Miami seems inspired under 36-year-old quarterback Ryan Fitzpatrick, on his eighth NFL stop that includes four seasons with Buffalo (2009-12).

Last month, in a stadium he knew all too well, Fitzpatrick was 23-of-35 passing, tossed a touchdown, was intercepted once but not sacked. He also rushed for a score. The Dolphins outgained the Bills 381 yards to 305, dominated time of possession by seven minutes and converted 54 percent of their first downs.

In other words, there’s more to this game than the two teams’ records, particularly for Buffalo.

After once sitting comfortably in the AFC’s top wild-card position, the Bills are still there, but shaky. Indianapolis and Oakland are 5-4 and Tennessee and Pittsburgh are 5-5. By tomorrow evening, it could be a three-way tie atop the wild-card race.

AND MAYBE that’s why Buffalo coach Sean McDermott was a bit chippy in Wednesday’s abbreviated media day press conference.

When pressed if he was satisfied with the Bills ranking 25th in average points scored (19 per game) and 23rd in yards gained (337), McDermott requested specifics from the questioner and several times repeated some version of “I want to move the ball and score points,” before walking off.

And earlier, he was a bit defensive about the defeat at Cleveland, noting, “We lost one game (before) this past weekend. That’s what we have to keep in perspective. We all wanted to go out and beat the Browns. But we have to turn our attention to getting better and moving forward to the Dolphins.

“They’re a team that has come off of a good win in Indianapolis, a good football team that’s well-coached. We’ve got to turn our attention and focus on what we can control.”

Offensive coordinator Brian Daboll offered a bit more insight into Buffalo’s offensive struggles, especially the 5-of-13 on third down against the Browns.

“We had plenty of opportunities; third and two-to-five (yards),” he said of the Cleveland loss. “You’d like to skip third downs … it’s a tough down as it is. We need to do a better job, all of us; it starts with me, of converting in those situations. The third-and-shorts were costly for us.”

He admitted, “We have to find a way to score more points; whether that’s running or passing. When they try to stop one thing, that needs to open up other things, and we need to do a good job executing that. Is there a time you need to run it no matter what … absolutely.”

MEANWHILE, the Dolphins have undergone a resurgence.

“Any time you win, that’s a confidence builder,” Miami coach Brian Flores admitted, “but at the same time, I’ve said this before: when you deal with adversity or mental toughness, my opinion is, one, how you deal with failure and, two, how you deal with success. We’ve had a little bit of it (but) I don’t think there’s any reason to bask in the glory.

“We’ve won two games. Given where we were earlier in the year I think there’s definitely a little bit of confidence, but I think there’s also an understanding that things can go right back to the way they were. If we don’t work at it, spend a little less time in preparation, a little a less urgency and commitment in a walkthrough or a practice or a meeting, that’s the difference.”

He added, “How many plays in this league are a shoestring tackle difference between a 6-yard run and a 60-yard run; or a toe clip is the difference between a sack and a 60-yard pass? Hopefully we don’t lose that from a preparation standpoint because we’re excited about what happened last week but we also need to forget about last week.”

Flores continued, “We’ve got this tough opponent. When I see (Buffalo QB) Josh Allen running around on film, I know this is a tough challenge.

“Whether it’s Allen or (Frank) Gore or (Devin) Singletary or John Brown, that offensive line, defensively they’ve got guys everywhere; yeah, I have confidence in this team, but I also know this is the National Football League and every game is tough. They’re going to come in here and try to knock our heads off in a tough, physical game and we have to be ready for that.”