Gore has been there before.
Gore might have just finished his 15th NFL season as a member of the Buffalo Bills, but he is very much still a member of the 49ers -- the organization for which he played his first 10 NFL seasons. Gore had dinner earlier in the week with team executives, including CEO Jed York.
And Gore was in the 49ers' locker room following the team's 31-20 loss to the Kansas City Chiefs in Super Bowl LIV on Sunday night.
"He told me to just keep my head up, and he's proud of me," Mostert said of Gore. "And he's been watching me work. For him to say that to me is very special because he's a Hall of Famer, and I look up to him.
"It was cool that he came up and talked to me, and makes me feel like we're going to bounce back."
Mostert and Gore know each other because of a mutual friend. Duane Carlisle was the strength and conditioning coach at Purdue with Mostert, and he worked in that same capacity with the 49ers early in Gore's career.
Gore has played in one Super Bowl. He rushed for 110 yards and a touchdown in the 49ers' 34-31 loss to the Baltimore Ravens in Super Bowl XLVII. So he knows the feeling.
Mostert made a name for himself in the postseason. He broke Gore's single-game 49ers rushing record in the NFC Championship Game with a 220-yard, four-touchdown performance in the 49ers' 37-20 victory over the Green Bay Packers.
On Sunday night, Mostert gained a team-high 58 yards and a touchdown on 12 carries. After Mostert's touchdown gave the 49ers a 20-10 lead late in the third quarter, the 49ers managed only 49 yards on their final four offensive possessions.
"I tried to leave before the confetti because I knew once that confetti hit, I'm going to be really, really messed up," said Mostert, who was also consoled by Chiefs running back and friend Damien Williams.
"It's one of those things, we didn't get the job done. It's unfortunate. We left the trophy out there."
Frank Gore gives Raheem Mostert encouragement after 49ers' Super Bowl loss originally appeared on NBC Sports Bay Area