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Germany havealready qualifiedfor the knockout stages, and Ecuador could still secure their spot with a win.
As well as being available on BBC Football's, the watchalong will also be on Sidemen's MoreSidemen
Four members of the Sidemen (Tobi Brown, Simon Minter, Ethan Payne. Josh Bradley) will host the pre-match build-up from 20:45 BST before providing their own commentary and analysis through the game.
The watchalong and World Cup game will only be available to UK viewers.
"Millions of fans now follow football through creators, streams and social platforms alongside traditional broadcasts. This is about bringing those worlds together," Alex Kay-Jelski, director of BBC Sport, said.
"The Sidemen have built one of the biggest communities anywhere online. we're excited to work with them on something that has never been done before at a World Cup.
"It's a chance to reach audiences in new ways while still delivering the live action that matters most."
Ecuador v Germany is also live on BBC One. BBC iPlayer, with radio commentary available on BBC Radio 5 Live and BBC Sounds.
The other final group game in Group E, between Curacao and the Ivory Coast, will also kick off at 21:00.
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