The impoverished side from Vallecas are riding high in the league, currently just three points from fourth
spot, yet their extraordinary over-achieving has been down essentially to their form at home where they have won nine matches, a figure only surpassed by the top three in the division.
On the road has been a different story with Paco Jemez's side losing eight matches and William Hill price them at 16/1 (17.00) to claim what would arguably be the most famous victory in their history.
Barca meanwhile are offered at an unbackable 1/8 (1.12) while the draw is available at 15/2 (8.50).
However everything points to a comfortable Barca win on Sunday night, and the Catalans will fancy their chances of putting a few goals past a Rayo defence that, on the road, has been extremely leaky.
Indeed only two teams in the entire division have conceded more goals away from home than Rayo and backing a high scoring win for Barcelona is where the smart money should go.
The price of 3/4 (1.75) for Barca to win by three goals or more looks too good to turn down. In their last three encounters with the Vallecanos, Barca have netted a staggering 16 goals without reply and Sunday's game at the Camp Nou should see another comfortable home win with plenty of goals.
For some higher odds, backing Barca to score over 4.5 goals at 5/2 (3.50) looks an excellent option, one which has paid out seven times this season.
|Barcelona to win -3 handicap at 3/4 (1.75) with William Hill
||Barcelona to score over 4.5 goals at 5/2 (3.50) with William Hill|
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Phil Kitromilides is a sports anchor working on TV in Madrid. You can also follow Phil on Twitter.