The Fulham attacker netted his third goal of the tournament in the 76th minute when he stretched out to reach Donovan's low backpost cross and was thankful that the LA Galaxy superstar was able to send the ball in his direction when it was required most.
"Once Landon gets in those positions, he normally finds a player," Dempsey said.
"All I had to do was try to put myself in position that he could find me and I felt far post was the place to go. He hit it hard and low and all I had to do was put my foot on it.
"That's why after the goal I tried to go and celebrate with him because without that pass, there wasn't going to be a goal."
And Dempsey admitted that the Panamanians made life very difficult for he and his teammates with tight checking and close marking and praising them for producing a some quality throughout the tournament.
"It's a frustrating match in the sense that it was real tight," he added. "We found it difficult trying to get the ball between the lines.
"They're a very organized team. That's why they were in the semifinals. I think we showed our quality in being able to grind out a result even if it wasn't our best game and we now find ourselves in the final."