It's not difficult to pinpoint where it started to go wrong for Zenit. Last season they won the league by 13 points, lifting the title for the second time in succession. Although they were beaten in the Super Cup by Rubin, they began this season with four straight wins, despite a fixture list that looked testing: there was a 3-1 triumph at CSKA and then a 5-0 demolition of Spartak. At that stage, it looked as though Zenit might cruise to a hat-trick of Russian titles.

And then, quite abruptly, it all went horribly wrong, which is why Zenit go into Wednesday's Champions League game against an almost equally out of sorts Milan having won only one of their last five league games and taken a 3-0 beating from Málaga in their first Champions League game.

At first the slump in form seemed to be a dip caused by two tough fixtures in a row — the good news for Zenit is that from now until mid-November, they have as simple a run of fixtures as the Russian league is ever likely to throw up. They drew at Anzhi, who now top the table, then lost at home to Rubin. They beat struggling Mordovia and then they bought Hulk and Axel Witsel for a combined fee of €83m. After years of financial caution, this seemed like the moment when Zenit stepped up a level, when they might begin really to challenge the western European elite. The signings added quality and depth to the squad but, more than that, they were a statement of what Russian clubs could do.

What nobody seemed to have taken into account was how the Zenit dressing-room might react to newcomers, particularly massively hyped newcomers earning a reported three times more than even the best paid of the existing squad. "I'm not against foreign players but there must be a balance in the team," the captain, Igor Denisov, said. "Yes, the club has bought good players but do you think they are so much better than us that they should make three times as much?

"Zenit already have great players who have won as many titles as the new guys. I would understand if we got Messi or Iniesta. They would deserve any price. The principles of how the club is run are the most important as well as the respect of the Russian players, especially us – the St Petersburg natives who have always made up the core of a team like Zenit."

Denisov's complaints led to him being relegated to train with the youth team. "This measure is related to the fact that Denisov made an ultimatum to the club and refused to take the pitch against Krylya Sovetov, demanding that his personal contract be reviewed," said a statement on the club website. "FC Zenit believes that by breaking his agreement with the club, Denisov is behaving unprofessionally, thereby discrediting himself as a player of FC Zenit and the Russian national team, and causing serious harm to his reputation." Fabio Capello called him up to the national squad for the forthcoming World Cup qualifiers regardless.

The forward Alexander Kerzhakov also was expelled from the first-team squad "for improper behaviour" but was admitted back to the first-team squad after talks with the coach, Luciano Spalletti. It's understood that he has been treated more leniently because he did not demand a pay increase.

"As for Kerzhakov, he very clearly demonstrated that in these troubled times, he only wants to think about himself," Spalletti said. "We do not want to take along those who only think of themselves and do not want to move forward together with us."

Morale is clearly shot. With the exception of Vyacheslav Malafeev, after the crisis emerged, none of the Russian players in the squad had spoken to the media until Monday, skipping the mandatory post-match mixed zones. Speaking to Sport-Express, the midfielder Victor Fayzulin insisted that "none of the players have lost interest in winning, none are not training to fully capacity and none are taking it easy", when asked if the problem had become psychological. He then, slightly oddly, went on to answer a question that hadn't been asked: "This is definitely not the result of malice." There is clearly something seriously wrong when a player, unprompted, feels he has to deny his team-mates are losing games deliberately.

Spalletti himself has been criticised for his handling of the situation. "There has been a loss of control over the team – and a loss of mutual understanding within team sports creates a difficult moral atmosphere," the local Communist party said in an open letter to Russia's president, Vladimir Putin. "A series of very painful lesions has been replaced by open squabble between the leading players in the team to see who of them will get any more money. In this conflict, the public cannot decide who is right or wrong—all are equally ugly, selfish and greedy." The party seems to blame Spalletti for this, suggesting he should be replaced by "a stern coach from North Korea, where sport is part of the daily struggle for the independence and dignity of the country".

That prompted Putin to respond in an odd statement in which he seemed to be deflecting blame from the government and on to Gazprom, the sponsor whose largesse funded the signings – the tone perhaps conditioned by revelations that Zenit had claimed money from a state social insurance fund to pay players who had suffered injuries (something that may be legal but is clearly unpopular with the public).

"I also complain sometimes," he said. "I would like to note that it's the companies that buy the players and not the government. But fans also want to see world stars, not those who are on the wane but those who are at their peak."

Yet at least some Zenit fans clearly don't want to see Hulk: a hoax bomb with a photograph of him taped to it was left in a bag at their training ground last week. Hulk himself has insisted that he is perfectly happy at the club. "I think with time I will adapt," he told R-Sport, "but it is clear that the fact that they speak another language in Russia creates some difficulties. Still, I feel that the climate within the team is fantastic. I'm happy to play for Zenit, I have absolute support from everyone here. I'm trying to fit into the team and Zenit generally. I have no problems with anyone. I'm just trying to do my job the best way that I can. I'm very happy with my role in the team, which is to score goals."

So far he has managed one in a league game, in the 2-2 draw against Krylya Sovetov. Zenit's winless run was extended on Saturday as they could only draw 1-1 against Lokomotiv in a game ruined by a baffling red card for Loko's Roman Shishkin after 31 minutes, sent off for a second yellow after a foul on Hulk committed by Vedran Corluka. They now lie sixth, five points behind the leaders Anzhi with a third of the season gone.

A month ago, they seemed a side ready to scale new heights; now, they're desperately scrabbling to get back to where they were before they spent €80m. Both they and Milan will look at out of form opponents with some hope. "Spalletti has called this the match of the year," said Fayzulin. "If we win the mood and atmosphere in the team will improve and it will be a psychological turning point."