Victor Osimhen was not included in Napoli's official 23-man Serie A squad for this season, after the Nigerian striker's expected move away from the club failed to materialise.
Osimhen's 26 goals helped Napoli to their Scudetto win two seasons ago, but it has all turned sour since, and although the want-away player is still at the club, for now he plays no part in their plans.
Osimhen, 25, signed a contract extension with Napoli in December, keeping him at the club until 2026 and with a reported release clause of €130 million.
A month later, club president Aurelio De Laurentiis said Osimhen would leave at the end of the season, and in recent days his expected destination appeared to be Chelsea or Saudi Pro League club Al Ahli.
Negotiations went on until the transfer window closed in both Italy and England on Friday, but with Osimhen's wage demands apparently not met by Chelsea, it appeared he was on his way to Saudi Arabia.
Napoli, however, did not accept the offer from Al Ahli, who then signed Ivan Toney from Brentford for a fee ESPN reported to be £40 million ($53m), and signed Belgian Romelu Lukaku from Chelsea.
Later on Saturday, Lukaku scored on his debut for his new club to help Napoli to a 2-1 win over Parma in Serie A.
Speaking after the game, Conte said the failure to find an exit for Osimhen was the one blemish on Napoli's transfer window.
"We did not just bring in players to build on an existing team, but to fill certain empty slots, and I am happy with the work done by the club," he told reporters.
"If we had been able to sell Osimhen, it would've been an even better situation, but what happened cannot be changed and we move on."
However, he blasted the timing of the transfer window closing after the season has already begun.
"We take these three points knowing full well that we have to work after this absurdity of the transfer market," Conte said.
"Coaches have to train players who are going to leave and wait for players we've never worked with and don't know in what condition they'll be when they arrive.
"I hope that things can change in future, seeing as everyone is ready to change formats and rules."
Information from Reuters was used in this report.