The Chilean midfielder was Leverkusen's match-winner against Aris Saloniki on Thursday and Heynckes says he is just getting better and better.
"He has developed well and now feels the faith in him from the team and from outside," he told reporters. "Arturo is our most important player at present.
"He is on the way to becoming a really top player."
Kaiserslautern coach Marco Kurz will not just be focusing his attentions on blocking Vidal since he knows that Leverkusen have a strong team and not just several big individuals.
Even former Lautern striker Sidney Sam will not be getting any special attention.
"He is just one of 11 players who we have got to take care of," he said.
"Leverkusen are a different calibre - they are challenging for a place in the Champions League.
"We always want to get something from our games and, if we have a really good day, then we can also get something from Leverkusen."
The Red Devils can welcome Florian Dick back into their side after he missed the 3-0 win over Borussia Monchengladbach last weekend.
Heynckes could bring his captain Simon Rolfes back into the starting XI after he was given a rest in midweek.
Lars Bender is a doubt while Renato Augusto is back in the squad.