It is true that in most seasons the title winners tend to be the team who have performed best in the mini-league of the top teams, but that is not always the case and nobody seemed to be complaining last season when United won the title despite winning only one of their six games against the other top-four finishers. Liverpool were the best team in the elite mini-league last season with 14 points out of 18, but they fell four points short of United because they lacked consistency against the lesser teams.

There was no groundswell of opinion then that Liverpool deserved the title more, or that United were inferior champions, and it seems unfair to denigrate Arsenal's achievement in building a challenge on the foundations of consistency and adaptability in a highly competitive league.

And we must not forget that Arsenal have had to overcome the loss of Robin van Persie to injury in November, leaving them short of options in attack. Arguably that was a key factor in three of their four defeats against Chelsea and United, whose defences might have been tested more keenly if Van Persie had been fit.

Arsenal haven't won the title yet, of course, but should maintain their challenge today with a home win over struggling West Ham.

Chelsea and United face tougher games, with Carlo Ancelotti's team going to Blackburn, who rank eighth on home form, and United renewing rivalries with Liverpool.

United rate as the best bet among the three title contenders, with 1.65 for the win good value. Apart from the 1-0 defeat by Aston Villa - one of the best counter-attacking away sides in the Premier League - the defending champions have won all their other five home games against top-half opposition and 13 out of 15 overall in the league at Old Trafford.

Liverpool are more ponderous and less incisive than when they blitzed 4-1 at Old Trafford just over a year ago with their hopes of victory resting mainly on a return to form by Fernando Torres. Otherwise, Liverpool will be reliant on trying to stop United scoring, which will be extremely difficult with Wayne Rooney in the form of his life.

United have won 14 out of 15 when scoring at Old Trafford this season and Liverpool have lost seven of 10 when conceding on the road, so United have a great chance if they can score, and the probability of a United goal is much higher than their win odds suggest.

Chelsea's wobbly away form means they aren't a safe bet at Blackburn. Since winning 3-0 at Arsenal in late November to spark talk of a runaway title success, Chelsea's only victories on the road have been at bottom-four sides Burnley and Wolves and their record in their other five away games is drawn three and lost two.

Blackburn have lost only two out of 14 at home - and one of those was way back on the opening day, against Manchester City. Sam Allardyce always takes great pride in making life difficult for the top teams. Blackburn might need Chelsea to have an off day to stand a chance of winning, but certainly a draw is not out of the question.

Allardyce appears to have steered Blackburn clear of the relegation dogfight, which sees two crunch matches this weekend. Portsmouth v Hull is a clash between the bottom two at the end of a week that has seen both clubs plunged into fresh crisis. Hull parted company with Phil Brown and brought in Iain Dowie to save them from the drop, while relegation was made a near-certainty for Portsmouth when they were docked nine points for going into administration.

Portsmouth's players have rallied in adversity on many occasions already this season and they have a good form chance if they can play with pride again tonight, as Hull have taken only four points out of a possible 45 on their travels.

The other big showdown at the bottom is Wigan v Burnley - 15th against 18th - and again it is difficult to fancy the visitors, who have taken just a solitary point from 15 away games. Wigan haven't been the most reliable of teams despite proving capable of victories over Chelsea, Liverpool and Aston Villa, but they rate a good chance at the odds of beating a team who appear to have regressed since Owen Coyle left for Bolton.

Right on target

Goals scored by United in eight straight home wins against Premier League opposition: 29

Happy visitors

In their seven results away to bottom-half teams, Tottenham have notched up this many wins: 5

Home comforts

Of Arsenal's 12 victories on their home pitch, this many have been by a margin of two goals or more: 11

Shortlist: Mainz, Bochum, Crystal Palace, Barnsley, Swansea, Bilbao, Manchester United, Montpellier, Millwall.

Top five bets

1 Mainz on handicap

Solid chance against Freiburg, who have won only one of 12 at home

2 Swansea on handicap

Only two defeats all season against teams below them in the table

3 Bilbao home win

Going for sixth straight win at San Mames fortress

4 Manchester United home win

Wayne Rooney can make the difference against bitter rivals

5 Montpellier home win

Unlikely title challenge is founded on strong home record