City made an official complaint after striker Mario Balotelli was subjected to apparent monkey noises from the crowd during their 2-1 success at the Estadio do Dragao last night.
Tournament organisers UEFA, the European governing body, said today they were still waiting for reports from their match delegates, which are usually received one or two days after each match.
The matter overshadowed an excellent second-half performance by City, who came from behind to take the initiative after the first leg of the last-32 tie.
The Barclays Premier League leaders trailed to the Portuguese champions at the interval after a 27th-minute strike from Silvestre Varela.
But manager Roberto Mancini had dispelled any suggestion he may not take the competition seriously by fielding a strong side and they underlined their ability in the second half.
An own goal by Alvaro Pereira, who had been under pressure from Balotelli, gifted them an equaliser after 55 minutes and substitute Sergio Aguero snatched victory six minutes from time.
Midfielder Yaya Toure, who excelled on his return from the African Nations Cup, said: "We played great, we defended well and attacked well and played with great experience.
"But it is not finished, we have a second leg at home against Porto and they have fantastic players.
"We have to keep going because the second game will be the same, very hard.
"We have to continue to work hard to go on in these two competitions - the Europa League and Premier League."
The inspirational Toure had missed City's previous eight games and was eager to play despite the disappointment of Ivory Coast's energy-sapping penalty shoot-out loss to Zambia in the African Nations final last weekend.
The 28-year-old and his brother Kolo flew direct to Portugal and rejoined the City squad on the eve of the match.
Yaya Toure, who played the full 90 minutes, said: "I am a really good competitor and I love football - football is everything for me.
"I talked to the boss before the final of the African Cup and said, 'I want to join the team'.
"I wanted to try to play - maybe less minutes - but you have to play.
"I was very disappointed after the final and the penalties, it is always difficult but now it is finished we have to forget that.
"It was very important for my country and for me but now I have chance of winning the Europa League and the Premier League and this is very important for the club and me."
Toure has welcomed the prospect of playing alongside former captain Carlos Tevez once again as the club push for two trophies in the closing months of the season.
Tevez returned to Manchester earlier this week after more than three months' unauthorised leave in Argentina.
The 28-year-old has been given his own fitness plan and did not train with the first team ahead of their departure for Portugal.
Mancini has said Tevez must apologise for the events of the past four-and-a-half months before he will consider him for selection again.
The striker has not played for City since his infamous dispute with Mancini during the Champions League loss at Bayern Munich in September.
Toure said: "Carlos is a fantastic player and I hope he comes with us because we need him. He is an amazing player.
"I think for me it is not a problem - I think all the players would like him.
"He knows what he has to say to the boss and the rest of the players.
"I think, and especially for me, all the players would be happy if Carlos came back."
It remains to be seen how Mancini, who has also been disappointed Tevez's recent claim that the manager treated him "like a dog", intends to deal with the situation.
The pair have not met since Tevez reported back to the club's Carrington training base on Tuesday.
That meeting will now be further delayed as, with City not in action this weekend, Mancini has given players time off today and the Italian did not return to Manchester with the squad last night.
PA
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