Dennis and BMC covered the 20.9km course in a time of 23:11, six seconds faster than runner-up Etixx-QuickStep and 34 seconds faster than Tinkoff, which finished eighth.
Dennis now leads teammate Taylor Phinney in the overall by six 16 seconds and Tony Martin (Etixx-QuickStep) by 24. Sagan is fourth, 27 seconds back. Dennis has two more teammates win the top 10, with Manuel Quinziato and Greg Van Avermaet in seventh and eighth, respectively, 29 and 33 seconds behind.
"We finished with eight riders and we showed that there is a reason why we are the number one team in the world when it comes to the TTT," Dennis said.
"We weren't too stressed about performing. It was more about how much time we would take out of Sagan and Tinkoff," he said. "I am pretty satisfied with how we did. It wasn't perfect today. We still have some stuff to work on, and you never win easily, so everyone in the team suffered a bit, but we worked really well together."
By contrast, Tinkoff finished the stage with just four riders in contact, the team’s time taken on the fourth rider across the line. With two road stages remaining, Dennis has a comfortable-but-not-unassailable lead and three teammates close enough to provide multiple options for the team.
"I would have been happy to finish the TTT with an advantage of anything over 20 seconds, and I was aiming personally for around 30 to 40, so to get 34 seconds in the end and bring me to a 27 second advantage in the GC was good,” he said. "Although it is by no means a given that we will take the win, it will make it a bit easier.
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"We have Taylor Phinney, Van Avermaet, Quinziato and myself in the top 10 so we have a lot of cards to play in that sense and if one of us wins that's great. If that means the team wins but I lose, it doesn't matter if it is still BMC on the podium."
Sagan said after the stage that he’s not counting himself out and will target the multiple time bonuses on offer over the next two days, Etixx-QuickStep is a threat with three riders in the top 10, Martin being the closest at just 24 seconds down.
However, BMC director Fabio Baldato said the stage 5 win has given the team boost in both morale and confidence heading into the final two stages.
"We wanted to put in valuable time over Peter Sagan and Tinkoff, which we did, and we also put Rohan Dennis back in the lead and really strengthened our position in the general classification,” Baldato said. "A result like that gives us confidence ahead of the UCI World Championships, and we'll work hard to refine our team time trial even more. Now we need to focus on the GC and put all of our energy into defending our lead in the next two days."
The Eneco Tour continues Saturday with a 185.2km stage from Riemst to Lanaken and Sunday's 197.8km stage from Bornem to Geraardsbergen.
