Edin Dzeko scored the goal as City saw off the Baggies 1-0 in a Barclays Premier League clash short on intensity but not goalmouth action at the Etihad Stadium.
The result strengthened City's grip on second place in the table and mathematically ensured Champions League football for next season.
Mancini made eight changes for the match with Saturday's Wembley clash against Wigan in mind - resting the likes of Yaya Toure, Vincent Kompany, Pablo Zabaleta, David Silva and Sergio Aguero - but claimed his plans for the final were not settled.
He said: "Maybe, but I can change this. We have four days and I need to see the players the next couple of days. I will take the last decision on Saturday."
One player who might have forced himself into the reckoning was striker Dzeko, whose well-struck 35th-minute volley against the Baggies was his 14th goal of the season.
Mancini said: "Yes, could be [he is in contention]. I am happy because he scored an important goal. We have four days to recover from this game, so could be."