Comebacks were on the cards on day three of the Africa Cup of Nations as Senegal and Algeria turned the tables over respective opponents Ghana and South Africa to secure opening game wins in Group C.
His goal came with virtually the last kick of the game as he slotted home from the edge of the box to wrap up all three points for the Teranga Lions.
It was a deserved win for the Senegalese who overcame a slow start to dominate large periods of the second.
Andre Ayew opened the scoring for four-time winners Ghana with a penalty on 14 minutes.
Mame Diouf levelled for the 2002 silver medallists in the 58th minute as he headed against the crossbar before nodding home the rebound.
The game looked set to end in the tournament's fourth draw in five as the clock ticked over the 90th minute mark.
That was to change three minutes into stoppage time, however, as Sow fired home after several neat exchanges outside the penalty area.
"At half-time I said to the players that nothing was lost," said Senegal coach Alain Giresse.
"At 1-0 down with 45 minutes left, there was no doubts.
"We went back out on to the field with conviction.
"It is always better to take three points, but it doesn't mean we are guaranteed to qualify, just as the defeat for Ghana does not mean they are eliminated."
Africa Cup of Nations title favourites Algeria, who progressed to the final 16 at last year's FIFA World Cup, were also forced to come from behind to secure their opening win of the contest as they overcame South Africa 3-1.
It was an impressive fight back by the Desert Foxes, who went top of the table on goal difference in the "group of death".
Goals from Faouzi Ghoulam and Islam Slimani won a lively match for the top-ranked African team after a Thulani Hlatshwayo own-goal wiped out the lead Thuso Phala gave South Africa.
After dominating the first half, South Africa took the lead in the 51st minute when Phala slotted the ball home from eight yards after lovely build-up play from Tokelo Rantie and Sibusiso Vilakazi.
Rantie had the chance to double the South African lead just minutes later but crashed his penalty straight onto the crossbar - a costly mistake for the 2010 World Cup hosts.
The match was tied in the 67th minute when Hlatshwayo looped a Yacine Brahimi cross over his own goalkeeper, before Ghoulam hammered home his first international goal four minutes later.
Slimani wrapped up all three points for the favourites eight minutes from time when his shot from the edge of the area trickled through Keet and rolled over the line.
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