Tkachuk played just 16 minutes, 40 seconds in the 3-2 loss, which moved Vegas one win away from capturing its first Stanley Cup. He was clearly laboring in the game and skated only four shifts during the third period.
"Obviously, you want to be out there playing. Just was able to go out there at the end and tried to make some magic happen late but ran out of time," Tkachuk said.
Florida coach Paul Maurice wouldn't disclose what was affecting Tkachuk and wouldn't confirm his status for Tuesday's potential elimination game back in Las Vegas.
"We got two days off to assess that. Get some good rest and we'll make that decision [then]," he said.
What would it take for Tkachuk to miss Game 5?
"That's a tough question. I don't really want to talk about that right now," said the winger, who leads the Panthers with 11 goals and 13 assists this postseason.
It was the second-lowest total ice time for Tkachuk in the playoffs, behind Game 2 of the Stanley Cup Final, during which Tkachuk amassed 22 penalty minutes.
He did very little shooting in warmups and didn't have his usual velocity during Game 4. He managed four shots on goal on eight shot attempts, but Tkachuk went 10:41 between shifts in the third period as Florida attempted to rally from a 3-0 deficit.
"Matthew's been a grinder his whole life, and he was again tonight," Maurice said. "We were just looking and hoping to get into a situation where he could use what he had to give us and hopefully get on the power play a little earlier, I guess, than certainly at the end of the game."
The Panthers earned their only power play of the game with just under 18 seconds remaining after Vegas defenseman Alex Pietrangelo sent the puck over glass in the defensive zone.
There was speculation after the game that Tkachuk might have been feeling the effects of the Game 3 hit delivered by Golden Knights forward Keegan Kolesar. Tkachuk was pulled from that contest in the first period by NHL concussion spotters but was cleared to return in the second period. He would eventually score the game-tying goal ahead of Carter Verhaeghe's overtime winner.
"That's just not going to come out right now," Tkachuk said, when asked about the Game 3 hit.
Tkachuk was asked if his time off the ice in the third was due to being in too much pain.
"I don't even know how to answer that, really. Just trying to find a way out there to make it work tonight and came up just probably a second short," he said. "Time ran out there with me and [Sam Bennett] whacking away. Two more seconds there, you never know."
The end of the game was chaotic. The Panthers scrambled to get pucks on goalie Adin Hill (29 saves) in the final seconds of their 6-on-4 power play. Tkachuk had the puck on his stick right before the buzzer sounded. Then several scrums started, as Hill took exception to Florida defenseman Brandon Montour crashing his net after the horn sounded.
As garbage and plastic rats littered the ice -- fans had been frustrated with the officiating for the two games in Sunrise -- Hill earned a minor for unsportsmanlike conduct while Montour was given a charging minor and a 10-minute misconduct.
Tkachuk was given slashing and unsportsmanlike conduct penalties as well as his fourth 10-minute misconduct of the series. Tkachuk now has five 10-minute misconducts this postseason, the seventh player all time to have that many in a single postseason.
"A little mayhem after the buzzer there, but everyone on our ice there did our job to keep the puck out," Hill said.
Florida captain Aleksander Barkov said it was a by-product of a hard-played game.
"Those scrums are going to come. We were close to tying the game, and there are a lot of guys at the net, and those things happen," he said.
Teams up 3-1 in a best-of-seven Stanley Cup Final have won 36 of 37 series. The only team to rally from that deficit was the 1942 Toronto Maple Leafs, who came back from a 3-0 hole to defeat the Detroit Red Wings for the Cup.
But the Panthers do have something to cling to heading into Game 5: their shocking first-round win over the Boston Bruins after rallying from a 3-1 series deficit. It all started with a Game 5 overtime victory on the road, on the first of three overtime winners from Tkachuk in this run to the Stanley Cup Final.
"It was just like a really short-term mindset. Go in there, get the first goal in Boston, get it to overtime," Tkachuk said. "Just the longer games go against all these teams, all the pressure starts to shift to them. So it's going to Vegas, and the longer it goes, longer the game goes, the longer the series goes, all the pressure goes to them."
Maurice said that before Game 5 his players will be reminded plenty of that rally against the Bruins.
"We'll tell stories over the next two days, for sure, reminders of the energy level we brought into Game 5 in Boston," he said, "and we'll celebrate it. We'll celebrate it before the puck drops."