Chelsea's defeat by Sunderland was not so surprising, even if the manner of it was, and this weekend will give a much better idea of whether the champions are in serious trouble when they travel to Birmingham.
Unlike Sunderland, who appear to be a team on the up this season, Birmingham are on a downward spiral and have sunk to third-bottom in the Premier League table. They are exactly the type of struggling team that Chelsea normally put away with ease, but there is a groundswell of opinion suggesting Chelsea might run into problems again this weekend.
The critics point to the absence of first-choice central defenders John Terry and Alex, as well as influential midfielders Frank Lampard and Michael Essien. The feeling is that Nikola Zigic, the tallest player in the Premier League, might be able to trouble Chelsea's makeshift defence in the air, even though the Serb has made little impact since moving from Spain.
That explains why Chelsea are much bigger odds than would be expected for a visit to a relegation-threatened team. In the past four seasons - only one of which was a championship-winning campaign - Chelsea have won an incredible 21 out of 24 away games against teams that finished in the bottom six.
That record suggests defeat by Birmingham, or even a draw, would be a major turn-up, because on current form it seems reasonable to expect Alex McLeish's side to finish in the bottom six. There is an interesting element to that record in that it was 100 per cent in the three seasons before Carlo Ancelotti took charge, but last season Chelsea won three, drew two and lost one in that category.
This season, however, Chelsea have won easily in their two away games against teams in the bottom six - 6-0 at Wigan and 3-1 at West Ham. In addition, they won 2-1 at 14th-placed Blackburn and only dropped points in eight games against bottom-half opposition came in the 2-0 defeat at Liverpool.
With Liverpool unlikely to remain in the bottom half, despite their problems, Chelsea's form still looks solid. The only other teams to take points off them are Manchester City, Sunderland and Aston Villa - with the first two currently in the top six and Villa having been top-six regulars in recent seasons, there is nothing shocking about that form.
That means the negative reaction to the Sunderland defeat in the English press might be more wishful thinking than hard-edged analysis. In their desire to talk up a title race that previously seemed to be going all in Chelsea's favour, the pundits might well be exaggerating the champions' decline.
That is not to deny the drop-off in Chelsea's performance in recent weeks, notably in goals scored. They are five points below the total they had reached by the same stage last season and there is no doubt Ancelotti misses his big-name absentees.
The most surprising aspect of this week's press coverage, however, is the apparent belief that other Premier League teams will not only be encouraged by Sunderland's win to have a more attacking outlook against Chelsea but will have just as much success. That is a flawed argument, because only a handful of Premier League teams have a goalkeeper as good as Craig Gordon, attackers with the verve of Asamoah Gyan and Danny Welbeck, and highly promising youngsters such as Jordan Henderson and Nedum Onuoha.
That is why Sunderland have moved up the table this season, while Birmingham's lack of players with that quality has led to their decline. Birmingham are winless in six matches against teams in the top half of the table, with their two victories coming against Blackburn and Blackpool, who are both in the bottom seven.
Even if it is accepted that Chelsea are considerably weaker without their big names, the team Ancelotti is likely to put out against Birmingham will be of top-six quality at least and that should be good enough to get Chelsea back to winning ways.
The Premier League top three have all won on just four of the 13 matchdays so far this season and, with Manchester United at home to Wigan, the most vulnerable this weekend is Arsenal in their north London derby against Tottenham.
Under Arsene Wenger, the Gunners have an excellent home record against their neighbours, with 10 wins and four draws out of 14 in the league, but there has been some narrowing of the gap since Harry Redknapp took charge at White Hart Lane.
Redknapp's first away game was a visit to the Emirates Stadium in October 2008 and he came away with a share of the spoils as two late Tottenham goals secured a thrilling 4-4 draw. Last season was a different story, with Arsenal winning 3-0, but Redknapp has had a win and a draw in his two home league derbies, which shows Tottenham have moved closer to the standard of their rivals.
The best bet might be a high-scoring match, with both managers having strong attacking instincts.
Bolton, whose fifth place does not unduly flatter them, look a reasonable home bet against Newcastle, while Aston Villa could land big odds at Blackburn. Gerard Houllier is giving youth a chance at Villa and their performance against Manchester United last weekend suggests it is starting to pay dividends.
Shortlist: Chelsea, Oldham, Villarreal, Espanyol, Real Sociedad, Getafe, Sochaux, Nurnberg, Juventus
Top five bets
1 Chelsea away win
First-rate opportunity to silence the doubters, for now at least
2 Villarreal home win
Have won the last three at home against Valencia and look strong again
3 Espanyol home win
Like Villarreal, they can maintain their 100 per cent home record
4 Getafe home win
Recent defeats against top-eight sides mask decent underlying form
5 Juventus on handicap
Unbeaten in 11 in all competitions, although draw rate is highTopics: English Footballers Carlo Ancelotti