Guimaraes went into the clash as huge favourites, eyeing a comfortable home win to leap above third-placed Sporting Lisbon, who are in action against Academica on Sunday.
But the match proved far tighter than anticipated, as Simeon Nwankwo put the visitors ahead with 27 minutes gone, turning in Diogo Viana’s left-wing cross.
Evaldo doubled the away side's lead early in the second half, but Guimaraes' fightback started 11 minutes from time, Ricardo Valente finding the net.
And deep into stoppage-time, Andre converted a penalty to salvage a point for Rui Vitoria's side.
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