Two hugely contrasting semi-finals have conspired to produce what could potentially be one of the most intriguing FA Cup finals for several years. After Chelsea overcame a tactically inert Aston Villa side in a bland first semi, Portsmouth injected some life into the latter stages of this year’s competition with an unexpected and somewhat fortuitous win over Tottenham Hotspur in the second. With Avram Grant set to take on his old club and Carlo Ancelotti ready for his first Wembley experience, what can we expect from the two sides in terms of their tactical approach to English football’s showpiece?

Chelsea’s likely system is relatively straightforward to predict. All season Ancelotti has favoured a flexible 4-3-3 formation where the switch to 4-3-1-2 can be made easily when necessary. With Jon Obi Mikel deployed as the anchorman in the midfield, Frank Lampard and the third midfield player (one of Michael Ballack or Deco in recent times) are given a greater creative license, breaking forward to construct and support attacking  Of that more advanced trio, Didier Drogba adopts the central position with Florent Malouda and Joe Cole or Nicolas Anelka attacking on the flanks.

However, there could be a few changes in personnel for the Blues by the time the final comes around on May 15th. Michael Essien, the Ghanaian midfielder who has been out since January with a knee injury, is expected to make a return to the side in early May, with Ashley Cole expected to complete his recovery a week earlier. The recovery of the pair, two of the Blues’ most influential players, will give Ancelotti’s team an added dynamism, both a more robust presence in the centre of midfield and greater positional awareness and attacking intent at left-back, not that Ballack or Yuri Zhirkov have underperformed in their absence.

Portsmouth, on the other hand, have a plethora of problems to overcome ahead of the final, with contracts involving unpayable performance-related bonuses threatening to rule several players out of the final. The most high-profile of these jeopardising arrangements is that of on-loan Ivorian striker Aruna Dindane, Pompey having previously agreed to pay his parent club Racing Club de Lens £4m upon the player’s 22nd appearance for the South Coast outfit. Having now played 21 games and with Portsmouth in a dire financial position, it looks highly unlikely that the club will be in a position to reach a financial agreement with the French club which would allow Dindane to take to the field at Wembley.

The club’s reported inability to pay out on bonuses may also obstruct the likes of Richard Hughes, John Utaka, Jamie Ashdown, Papa Bouba Diop and Kanu from playing in the final – although their situations are not quite as convoluted as Dindane’s and there is a possibility that some of the players would be willing to forgo some aspects of their contractual arrangements in order to participate against Chelsea. As a result, it is difficult to predict both the system and personnel that Avram Grant will adopt on May 15th, but if we presume that the majority of the financial technicalities are ironed out in time for the game – although Dindane’s looks unlikely to be resolved – then we can attempt to put together a picture of how Pompey might approach its second FA Cup final in three seasons.

Since his appointment at Fratton Park in late November, Grant has continually tinkered with his team’s tactical approach, deploying a combination of 4-3-3, 4-5-1, 4-2-3-1 and 4-1-3-2 at various stages of the season. However, recently it has been with the 4-2-3-1 set-up that the Israeli Coach has enjoyed the most success, recent wins over Burnley, Hull City and of course Tottenham in the semi-final going some way to proving the formation’s suitability for this particular group of players.

A flat back four will be crucial when faced with the attacking capabilities of Chelsea, but a recent ligament injury to Algeria left-back Nadir Belhadj may mean Grant is unable to select his first-choice defence. Should Belhadj miss out then Steve Finnan would likely to switched to the left, with the adaptable Hayden Mullins slotting in at right-back. Pompey will also need strong performances from their two holding midfielders, likely to be Mark Wilson – who Grant has transformed into a reliable defensive midfield player of late – and Michael Brown, both of whom will be relied upon to break-up Chelsea attacks and strangle the service to Drogba at source. Jamie O’Hara, Kevin-Prince Boateng and Quincy Owusu-Abeyie or John Utaka will form an advanced midfield three, providing the team with the width and penetration that will be so important if Portsmouth are to be in with any sort of chance of overcoming their London opponents. They will likely support a lone striker, almost certain to be the club’s semi-final hero, Frederic Piquionne, who will attempt to get amongst the Chelsea defence, perhaps creating space for O’Hara to come from deep and link-up in attack.

With Portsmouth, a beleaguered side already consigned to the fate of relegation, taking on Chelsea, the likely league champions, this does not appear to be the best of matches to have a flutter on, so slim is Pompey’s chance of overturning last year’s FA Cup winners. However, the disciplined and spirited performance Avram Grant’s side produced against Tottenham in the semis may have persuaded a few punters to take a chance, Portsmouth currently best priced at 9/2 by Bet365. Chelsea, predictably, are comfortable favourites, with some bookmakers pricing them as short as 1/8.

There may, however, be some money to be made by predicting the final score or scorers. When the two teams met at Stamford Bridge back in December Chelsea ran out 2-1 winners with goals from Anelka and Lampard, Piquionne getting on the score sheet for Pompey. More recently, when the teams clashed at Fratton Park, the Blues took Grant’s team apart, winning 0-5 courtesy of a brace each from Drogba and Malouda, with Lampard again getting in on the act with a goal. If these previous encounters are anything to go by, it could well be worth laying on Lampard or Drogba to be first scorer – or to score at any time – with Piquionne perhaps being the option for those of a more romantic disposition.

In terms of the scoreline, 2-0 to the London club is priced the shortest (5/1) with a repeat of their 0-5 win out at 22/1. If you think Portsmouth have a serious chance of springing what would be a huge upset, then William Hill are offering 12/1 on a 1-0 win and 28/1 on 2-1. It’s unlikely but, as we all know too well, the FA Cup has a funny habit of producing the unforeseen.

Chelsea probable starting XI (4-3-3): Petr Cech; Branislav Ivanovic, John Terry, Ricardo Carvalho, Ashley Cole; Jon Obi Mikel, Michael Essien, Frank Lampard; Joe Cole, Didier Drogba, Florent Malouda.

Portsmouth probable starting XI (4-2-3-1): David James; Steve Finnan, Ricardo Rocha, Aaron Mokoena, Nadir Belhadj; Mark Wilson, Michael Brown; Quincy Owusu-Abeyie, Jamie O’Hara, Kevin-Prince Boateng; Frederic Piquionne.