PITTSBURGH -- Baltimore Ravens coach John Harbaugh said injuries affected his decision to go for a potential game-winning 2-point conversion Sunday against the Pittsburgh Steelers, instead of settling for a tying point-after kick.

With 12 seconds remaining in regulation, Lamar Jackson's pass on the 2-point conversion went off the outstretched left hand of tight end Mark Andrews as the Ravens fell to the Steelers 20-19.

Asked why he went for two instead of the PAT to force overtime, Harbaugh said: "[We're] trying to win the game right there. We were pretty much out of corners at that point in time. It was an opportunity to try to win the game right there."

Ravens Pro Bowl cornerback Marlon Humphrey grabbed his left shoulder when trying to tackle Steelers wide receiver Diontae Johnson on Pittsburgh's go-ahead, 5-yard TD with 1:48 to play. The Ravens fear Humphrey suffered a season-ending injury on the play, a source told ESPN, confirming a report by NFL Network.

Harbaugh said Humphrey will undergo an MRI and declined to specify the injury.

"It could be a while for Marlon," he said.

The analytics slightly favored Baltimore going for two points (47.1%) over the kick (46.5%), according to ESPN Stats & Information research.

Jackson backed Harbaugh's decision.

"I want to win," Jackson said. "I didn't want to go to overtime anyway."

With the Ravens trailing 20-13, Jackson capped a 60-yard drive by hitting Sammy Watkins for a 6-yard touchdown. Then, on the 2-point conversion, Andrews was uncovered in the right flat but Jackson had to step up and adjust his throw because Steelers linebacker T.J. Watt was in his face.

Jackson is now 3-of-10 on 2-point conversions in his career (either rushing or passing). That's the second-worst conversion rate in the past 20 seasons among 40 players with 10-plus 2-point conversion attempts, according to ESPN Stats & Information.

"T.J. Watt's got range. He's a long guy," Jackson said. "I had to throw around him and try to make something happen. That's all. Just came up short."

Andrews accepted the blame for the failed conversion.

"[It] was a good play call," Andrews said. "I came wide open. Lamar threw a great ball; I just didn't make the play."

In the past three seasons, teams are 3-for-8 (37.5%) on 2-point conversion attempts when down by one point in the fourth quarter. They are 10-of-23 (43.4%) in these situations since 2000.

Harbaugh was pleased with the play call, not the execution.

"It was a game of inches," Harbaugh said. "You saw the Al Pacino speech in 'Any Given Sunday.' There you go. That's football. It's just that close."

This marked the fourth time in five meetings that a Ravens-Steelers game was decided by five points or less.

Steelers coach Mike Tomlin wasn't surprised by the Ravens going for the win.

"They aggressively play analytics," Tomlin said. "From that standpoint, they're predictable."

Baltimore allowed Pittsburgh to score on all three of its fourth-quarter drives and then lost its top corner in Humphrey. Entering Sunday's game, the Ravens were already dealing with injuries at cornerback, with all their active ones -- Anthony Averett (shoulder/ankle), Tavon Young (illness), Jimmy Smith (neck/ankle) -- missing at least one practice last week.

The Baltimore secondary has already dealt with season-ending injuries to two starters in the secondary: cornerback Marcus Peters (knee) and safety DeShon Elliott (torn biceps/pectoral muscles).

"We've got a lot of injuries, so we've been dealing with stress all season, and we've still been able to overcome it," Ravens nose tackle Brandon Williams said. "So, that's what we plan on doing. It's a 'Next Man Up' mentality, so the show must go on."

Despite the loss, the Ravens (8-4) still lead the AFC North by one game. Baltimore next plays at the Cleveland Browns (6-6), who are coming off a bye.

ESPN's Brooke Pryor contributed to this report.