Philadelphia is 0-7 in overtime games this season.
"We've got to get that figured out," coach John Tortorella said. "We battled back three times tonight. Now we've got to figure out end of games, figure out how to score that goal."
Coyotes coach Andre Tourigny is encouraged with wins against the Boston Bruins and Flyers after Arizona won only once in the final 11 games (1-7-3) of a 14-game road stretch.
"Give the Flyers credit, they were physical and hard-working … and came here and took a little bit of advantage of maybe our mental fatigue," Tourigny said. "But we like the resilience of our group. We found a way to win the game."
Keller put the Coyotes ahead 1-0 at 12:46 of the first to end a 10-game goal drought with a wrist shot from the high slot on the power play.
Arizona was 1-for-29 on the power play in its previous 10 games.
"He is playing way different than he did at the start of the season," Tourigny said of Keller, who missed the final month of last season with a broken leg. "He's playing with more pace, he has more speed, he puts more pucks on the net. In my opinion, he's back to where he was last year."