Aston Villa 2 Chelsea 0:It was the day when the Premier League season began to make good on its promise. The expectation that the major clubs will have to endure distress more frequently was fulfilled as a mediocre Chelsea, stifled and stopped, were left last night as sullen occupiers of fourth place in the table. All that rose steeply for the visitors was the frustration that Martin O'Neill causes in them. This was Chelsea's first defeat in the league since they were beaten 2-0 at Anfield in January.

Jose Mourinho will have counted last season's pair of draws with Villa as significant in the loss of the title and the nature of the match should concern the Stamford Bridge club. Roman Abramovich was reported at the weekend to be still dissatisfied with Mourinho's type of football. There was compelling if circumstantial evidence for that here in his sullen expression and early departure from his seat.

He did go to the dressing room and shook hands with the players when Mourinho was elsewhere, conducting post-match interviews, but solidarity is not synonymous with approval. While a fan with a grievance might settle for composing poison-pen letters in his mind, more profound steps are open to an owner.

The reported efforts of Abramovich to buy Ronaldinho, who dazzled with Barcelona yesterday, were a radical reaction to the cautious mediocrity that afflicts Chelsea now and again. It is an oddity that Mourinho, in his fourth season at the club, should be treated as if he were an unknown and rather dubious quantity.

The flaws at Villa Park are of the type known to exasperate a Chelsea proprietor craving spectacle. There was scant indication of any capacity in the side to respond to the opener from the debutant Zat Knight. Perhaps Abramovich will revert to championing the return of Andriy Shevchenko, who has been fit enough to represent Ukraine.

If England were looking for omens that Scott Carson can soon be their preferred goalkeeper they were disappointed because he was not granted many opportunities to shine, although he did put a Shaun Wright-Phillips attempt round the post in the 13th minute. It reflected well on Villa that mostly their goalkeeper was a bystander.

The game, in fairness to Chelsea, could have taken a very different course. After two minutes, Martin Laursen manhandled Wright-Phillips and Mark Clattenburg's refusal to award a penalty was perplexing.

Chelsea, all the same, were toothless after Knight had put them behind. The injured Frank Lampard was missed terribly and in a squad of this value others should have compensated. While Wright-Phillips did that for a while and Juliano Belletti, on his first start for Chelsea, had some good moments there was no mood of mounting inevitability.

Villa were resilient and, ultimately, deadly. O'Neill's selection was intriguing, since it had a very adventurous air yet also required those men of attacking intent to get behind the ball whenever Chelsea were in possession. John Carew alone had the luxury of staying upfield. As on too many occasions last season, the visitors' destiny lay with Didier Drogba alone.

The striker is a phenomenon, yet he was just about shackled at Villa Park. The efforts of Laursen epitomised the persistence when, in the 87th minute, he recovered to tackle Drogba after he seemed to have broken away on the right. Moments later, defeat for Chelsea was confirmed.

Ashley Young, the surprise selection in the England squad, at long last had scope to run freely on Villa's left and his driven ball across was turned into the net by Gabriel Agbonlahor.

Villa had not lacked encouragement. They found a defence, in which Alex started for the first time, that was ill at ease. After seven minutes, Agbonlahor was fed by Young and John Terry could not prevent him from spinning to hit a drive that Petr Cech parried. Later the Chelsea goalkeeper would tip over an attempt by Young.

Villa's progress since the first-day defeat to Liverpool here was remarkable, but Chelsea were more malleable material with which to work. After 47 minutes, Gareth Barry's corner was headed in by Knight.

Ashley Cole might have cleared but he preferred the awkwardness of kicking with his favoured left.

Mourinho is predicting the Premier League title race will be more open this season after seeing Aston Villa end Chelsea's 18-game unbeaten run.

"There has been a big input by teams outside of the top four so it will become more normal for the big teams to lose matches and points. The other teams have spent lots of money and brought players in to bolster their teams. Villa are one example but you can find a lot of other examples. It will be more difficult to play against these teams because they are better."

Mourinho also played down the significance of Abramovich leaving early. He said: "I think the owner leaves the stadium when he wants to leave. I went to see England-Germany the other day and I left early because I wanted to beat the traffic."