Simon will be aiming to become the first Frenchman to triumph at the prestigious grasscourt event.
Both singles semi-finals were absorbing in their own way, while the doubles that followed was filled with tension and excitement.
For it was the 2017 champion, Feliciano Lopez, a man cut from a very different cloth in today's game, a dedicated serve-and-volley left-hander who has played more consecutive Majors than any other man. In the victory, Lopez won 82 percent of his first serve points and 54 percent of his second serve points.
In the decider it was Auger-Aliassime who looked jaded and he was broken to love as Lopez went 3-2 up.
His match against Kyrgios included the standard bratty behaviour from the Australian bad boy but his younger rival kept his cool to win 6-7 7-6 7-5.
"I can not believe that I am here in the final again. It's insane how we old guys can still perform well", Lopez said. "I was feeling the ball great, even if I wasn't feeling great in the legs".
Previous year at Queen's Kyrgios was fined following his semi-final defeat to Marin Cilic after making suggestive gestures with a water bottle.
The earlier match between Simon and Medvedev on centre court was crammed full of interminable rallies regularly surpassing 30 strokes as they turned their match into the equivalent of a staring contest. That's what I do. "And I do it for long", Simon told reporters.
With similar styles, both players camped out on the baseline waiting for openings that rarely appeared.
The teenager's remarkable rise to the top of the tennis game continues apace, after he pulled off one of the biggest wins of his fledgling career so far, beating the number one seed Stefanos Tsitsipas in straight sets on Friday. He's serving out of his mind and is looking to finish points with confidence. On Sunday, he will become its oldest finalist.
Lopez will have a 10 minute break and then return to action to complete his doubles quarter-final clash against Dan Evans and Ken Skupski. The duo stayed on court for the semifinal and edged No. 3 seeds Henri Kontinen and John Peers. He was patient in eking out an advantage, but once in front, he scented blood and went for the kill, breaking serve at the start of the second set to race into a 3-0 lead.
Auger-Aliassime took the first set 7-5 after 51 minutes - the key being the winning of a high percentage of first serve points.
Feliciano Lopez is coming off a three sets win over Milos Raonic that took 33 games to decide. His opponent will be Gilles Simon, who prevailed in an all-French affair against compatriot Nicolas Mahut 7-6, 5-7, 7-6.
"It was a good match". There's the tennis player, and there's the person. He's not young anymore. I feel so happy I can not believe I am here.