Icardi has been replaced as club captain by Samir Handanovic by manager Luciano Spalletti, which has fuelled speculation over his future.
Spalletti confirmed that Icardi was unavailable this weekend because of injury and was undergoing treatment, per Football Italia.
However, the striker was at the San Siro to watch his team in action:
Spalletti has said that removing the captain's armband from Icardi was a "very painful and difficult" decision, per Football Italia. He also said the decision was "not against Icardi, but in favour of Inter."
Icardi was not part of Inter's squad for their UEFA Europa League clash against Rapid Vienna on Thursday.
Spalletti told Sky Sport Italia (h/t Goal) that "Icardi was called up and has decided not to travel to Vienna."
Icardi responded to the events with a cryptic post on social media:
The 25-year-old is an integral player for the Serie A side, but his contract expires in 2021 and he is yet to agree a renewal:
The Argentinian has been linked with a shock move to rivals Juventus after losing the Inter captaincy, per Goal. Manager Massimiliano Allegri offered his response to speculation his club could move for the striker.
"I don't know anything about the market. I prefer to go to the beach in the summer! The club takes care of the players and makes them available. Icardi is a forward who can score goals, but I leave the assessments to [Inter boss Luciano] Spalletti, who coaches him and knows him better."
Premier League side Chelsea are also reportedly interested in Icardi, according to The Sun's John Hutchinson.
However, Real Madrid have dropped their interest as they do not want to deal with Wanda Nara, Icardi's wife and agent, according to Jose Felix Diaz at Marca.
Meanwhile, Nara, has attempted to "smooth things over" with a "series of conciliatory messages on Twitter," per Football Italia.
Icardi's presence at the San Siro on Sunday is likely to be viewed as a positive sign in the current seemingly volatile saga between player and club. Yet speculation over his future at the club can be expected to continue until his contract situation is resolved.