The advantage is with Ecuador: after they held the Netherlands to a draw on Friday and beat Qatar in their opening match, they need only a point to qualify for the knockout phase.
Senegal, meanwhile, are only on three points having also beaten Qatar last time out but losing to the Netherlands in their first match.
This match will take place simultaneously with the other game in Group A, where Netherlands are firm favourites against Qatar, who are already out of their own World Cup. Here is everything you need to know.
When is Ecuador vs Senegal?
The match takes place on Tuesday 29 November at 3pm (GMT) - 6pm local time - at the Khalifa International Stadium in Al Rayyan.
How to watch
The game will be shown live in the UK on TV channel ITV4. Viewers can stream the match online via the ITVX app, formerly known as the ITV Hub.
Ecuador XI: Galindez, Preciado, Torres, Hincapie, Estupinan, Franco, Gruezo, Caicedo, Plata, Estrada, Valencia
Senegal XI: Mendy, Sabaly, Koulibaly, Jakobs, Diallo, Ciss, P Gueye, Ndiaye, I Gueye, Sarr, Dia
Ecuador win: 29/20
Senegal win: 21/10
Senegal have nothing to lose as they look to progress to the last-16 while Ecuador can afford to draw. The fitness of Valencia could be pivotal though even without their main man, the South Americans showed enough quality against the Netherlands to merit their favourites tag here. Ecuador 2-1 Senegal.