Prolific Costa could boss Arsenal's depleted defence
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Diego Costa is Chelsea's leading scorer this season with 21 goals in all competitions and he could have a major impact on the FA Cup final.
Arsenal will be well aware of the threat of Chelsea's main potential matchwinners, Costa and Eden Hazard, but they may find it difficult to stop them.
Hazard is the market leader in the man-of-the-match betting but the better value lies with Costa, the second favourite.
Costa went off the boil for a spell either side of Easter, failing to score in seven consecutive games.
But he looked hungrier during the run-in, notching three goals in Chelsea's last five matches, and will be eager to impress in what could be his last game for the club.
Doubts over Costa's future persist with talk of a possible move to China and his value to potential suitors would only increase with a strong performance in a high-profile cup final.
Costa is at his best when bullying opposition defenders and has a great chance to do just that against a severely understrength Arsenal back line missing Laurent Koscielny (suspended) and Gabriel (injured).
Rob Holding has been handed increased responsibility by Arsene Wenger and has done well. However, the 21-year-old is still learning the game at the highest level and the task of marshalling Costa looks tough.
Arsenal's most likely matchwinner is Alexis Sanchez, although he has been suffering from a thigh injury and his fitness is not likely to be 100 per cent. However, the Chilean will be feeling confident after scoring five goals in his last four appearances.
Arsenal players feature more prominently in the first booking betting.
Three Gunners players are in the top four in the market with Granit Xhaka at 8-1, Shkodran Mustafi 9-1 and Francis Coquelin 10-1.
Xhaka has the poorest disciplinary record of any Arsenal player this season, picking up 11 yellow cards and two reds, and he deserves to be favourite.
There is no love lost between the clubs but referee Anthony Taylor may not have to reach for his notebook often and there is value in taking bet365's 10-11 quote that the contest features fewer than 4.5 cards (extra-time not included).
Arsenal finished tenth in the Premier League fair play table - averaging 1.84 cards per game (67 yellows and three reds), while Chelsea were 14th with an average of 1.89 (72 yellows and no reds).
Adding the two averages together brings a figure of 3.73 – well short of bet365's cards line.
The big occasion and the tribal nature of the match help to explain the prices but Arsenal's league contests against Chelsea went off fairly quietly with only two yellow cards shown at the Emirates and two again at Stamford Bridge.
It could be different at Wembley but there seems a greater chance of the card count coming in beneath bet365's line than the other way round.
D Costa to be man of the match
1pt 11-2 bet365
Under 4.5 total cards (90 minutes)
2pts 10-11 bet365