LONDON - Soccer has some great rivalries: Barcelona vs. Real Madrid, Boca Juniors vs. River Plate, AC Milan vs. Inter Milan.

No one really expected Jose Mourinho vs. Roman Abramovich to join that illustrious group.

The power struggle at Chelsea ended Thursday when it became obvious that the egos of the outspoken coach and the billionaire owner couldn’t get along.

Mourinho, the talented Portuguese coach who led the Blues to their first English league title in half a century, walked out of Stamford Bridge and left Abramovich to find someone else to win the title he wants more than anything: the Champions League.

Abramovich had already been the Chelsea owner for a year before he persuaded Mourinho to leave FC Porto after he won European soccer’s biggest club title for the Portuguese team.

The wealthy Russian believed Mourinho would do the same for Chelsea and, with the millions they had to spend in the transfer market, few people bet against him.

It never happened.

Chelsea twice lost in the Champions League semifinals and, on Tuesday, began this season’s campaign with a tame 1-1 draw against Rosenborg, a Norwegian club the Blues were expected to beat by three or more goals, especially at Stamford Bridge.

With Chelsea also falling behind in the Premier League title race — a 0-0 draw with Blackburn coming after a 2-0 loss at Aston Villa where Abramovich very publicly walked out before the final whistle — there were signs something was wrong at the club.

Like last season, when it became clear it was Abramovich, rather than Mourinho, who bought Andriy Shevchenko from AC Milan for $59 million. The Ukraine striker, who scored 173 goals in seven seasons for Milan, struggled to find the net for the Blues, making Mourinho even more frustrated.

The manager and the owner barely spoke to each other, and there was another problem during the offseason when Abramovich added former Israel coach Avram Grant to the backup staff, again without Mourinho’s approval.

Mourinho no longer felt in charge of his team. It may be significant that Grant and assistant manager Steve Clarke, who was already at Chelsea before Mourinho arrived, were put in charge of the team while the coaching staff of Baltemar Brito, Rui Faria, Andre Villas and Silvino Louro all followed Mourinho out the door.

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Abramovich was reported to have been unhappy that Chelsea didn’t play crowd-pleasing soccer. The fact that the Stamford Bridge attendance for the game against Rosenborg was about 14,000 below capacity may have supported his argument.

When it emerged that Mourinho had gone, there was a debate whether he quit or was fired. Whatever happened, the next time they meet, they likely will be opponents for real instead of just fighting against each other inside their own club.

While Abramovich never speaks to reporters, Mourinho is the media’s dream manager. He’s talkative and often controversial, with an amusing way of explaining himself.

The day before Chelsea played Rosenborg, Mourinho was asked to comment on his injury list, with the likes of Frank Lampard, Didier Drogba and Michael Ballack all missing action. He gave this colorful response:

“It is omelets and eggs. No eggs — no omelets,” Mourinho said. “It depends on the quality of the eggs. In the supermarket you have class one, class two or class three eggs and some are more expensive than others and some give you better omelets. So when the class one eggs are in (upscale store) Waitrose and you cannot go there, you have a problem.”

While he may have been talking about injuries, the eggs-and-omelet analogy could have been a reflection on his inability to strengthen his squad with the likes of top quality players such as AC Milan’s Kaka and FC Barcelona’s Ronaldinho.

Mourinho’s five-year contract at Stamford Bridge promised much more than an omelet. Chelsea fans were expecting a grand banquet and never really got past the first course.