Former Tottenham striker Dimitar Berbatov says it's no surprise Harry Kane is upset with being tethered to his Spurs contract.
However, Berbatov believes Kane has been "naïve" in his negotiations with the North London club.
Kane has been left out of the Tottenham squad that's travelled to Portugal for the first leg of their UEFA Europa Conference League playoff with Pacos de Ferreira.
The 28-year old has instead remained in London, as he looks to regain full fitness following a shortened pre-season.
Manchester City are believed to be waiting in the wings with a £150million (€176m) bid for the England captain.
Kane is believed to have had a gentleman's agreement with Spurs chairman Daniel Levy that would allow him to leave if the club missed out on Champions League football last season.
But Levy, and Tottenham, are holding Kane to his contract which does not expire until 2024.
"If they did speak at the end of last season and they had a gentleman's agreement which has been broken, it isn't a great situation and it's no surprise that Kane is pissed off," Berbatov told Betfair.
"I have been in this situation and all I have to say is that they should have expected and anticipated this.
"Kane's team shouldn't have been so naïve with this situation because football is a business.
"Of course, we like that gentlemen's style of shaking hands and saying, 'yes, you have my word', but sometimes in football it doesn't work like this and you get angry.
"You have to expect for these things to happen and plan how to avoid it or react to it when it happens."
While Kane won't feature in Europe this week, Nuno would not be drawn on whether the striker will make his first appearance of the season against Wolves at the weekend.
"I cannot answer that," the Spurs boss said, "What I can tell you is he's better.
"He's getting his fitness better and better each day. He worked today, he's going to work tomorrow and he's going to join the group on Friday.
"And on Saturday we're going to make a decision on who's going to be involved in the next game."