The west Africans could have ensured qualification to the next phase in Russia in Sunday's second group match against Japan but are now on shaky ground after playing out a 2-2 draw, even if the permutations are still weighted in their favour.
On Thursday, as the group phase draws to a close, Senegal only need a draw to advance but victory for Colombia will put them into the next round instead, leaving Senegal eliminated if Japan avoid defeat against Poland in Volgograd at the same time.
Colombia could also advance with a draw, but only if Japan lose.
Japan and Senegal head the group on four points each with Colombia one behind after rebounding with a 3-0 thumping of the now-eliminated Poland in Kazan on Sunday.
It was an emphatic reaffirmation of their potential after 10-man Colombia, quarter-finalists in Brazil four years ago, had suffered an upset defeat in their opening game to Japan.
The likes of Falcao and Juan Cuadrado underlined the quality in a team that welcomed back James Rodriguez, top scorer at the last World Cup, to a leading role after starting him from the bench against Japan.
"The team played as a unit and the football emerged from this unity. It led to the goals and now we have a good position in this World Cup," Colombia coach Jose Pekerman said after the victory.
Senegal will be concerned by the potential of letting slip a favourable position, after kicking off the tournament with a 2-0 win over Poland and then being in command against Japan, only to prove unable to secure all the points.
"We still have our destiny in our own hands," insisted defender Kalidou Koulibaly, but team mate Alfred Ndiaye warned of a hard task ahead.
"Colombia's style of play is similar to ours, very physical, moving forward quickly. We know that we must not lose this game. We're aware that we will have to give everything to qualify," Ndiaye said.
(Writing by Mark Gleeson in Nizhny Novgorod; Editing by John O'Brien)
