Cobie Smulders, Neil Patrick Harris Cobie Smulders, Neil Patrick Harris

"Someone is going to ruin this wedding."

That's what Robin (Cobie Smulders) says in the first sneak peek from the upcoming final season of How I Met Your Mother. But who will be the one to rain on her and Barney's (Neil Patrick Harris) big day? You may think it's Ted (Josh Radnor), but the video below may prove otherwise.

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Still, Lily (Alyson Hannigan) will stop at nothing to keep Ted from acting on his confused feelings — even if that means tackling him to the ground. Check out the video below to get your first look at the final season:

How I Met Your Mother premieres Monday, Sept. 23 at 8/7c on CBS.

(Full disclosure: is owned by CBS.)