Zlatan Ibrahimovic has said that not knowing how long he would be on the sidelines for was the hardest part of his recent heel injury.
The 33-year-old returned to competitive football in Paris Saint-Germain's 2-0 Ligue 1 win over Marseille on Sunday, his first appearance since Sept. 21.
The injury to his left heel had mystified both club and national team medical staff, and Ibrahimovic said the uncertainty over the exact nature of the problem had been a major concern.
"The doctors didn't know when I would come back, and that was the worst thing," the former AC Milan forward said.
"If they had said to me: 'You're out for two years,' I would have known what I had in front of me. But I didn't have that. I had to be patient, work day after day. It was very tough mentally.
"It's no fun to be injured for such a long time in such conditions."
Ibrahimovic's 24-minute cameo against Marseille, in which he played a central role in Edinson Cavani's clinching goal in the 2-0 win, has raised hopes that he can lead Sweden in Saturday's crucial Euro 2016 qualifier in Montenegro before Tuesday's friendly against France in Marseille.
"I am totally focused on that game. It's the first one and it's very important in our qualifying campaign for the Euros," Ibrahimovic said.
"Before playing against Marseille last Sunday, I didn't know whether or not I would be capable of playing 30 minutes with PSG. But in the end, it went well.
"But for a month and a half, I wasn't able to do any running. I had started running just three days before the game. With adrenalin and the fans, I was just happy to get back on the pitch. That gave me added energy. I did what I could."