Moments later, the Derby keeper was involved once more when he saved John Eustace's header with his feet.

BBC: Watford 0-1 Derby

Captain John Eustace will miss the clash as he serves a one-match suspension.

BBC: Watford's Stephen McGinn set for long lay-off

John Eustace had an opportunity at the other end but the experienced midfielder headed straight at on-loan goalkeeper Asmir Begovic.

BBC: SPORT | Football | Championship | Ipswich 1-1 Watford

But midfielder McGinn is likely to join defender Lloyd Doyley on the injury list, while captain John Eustace will serve a one-match ban after receiving two yellow cards at Doncaster.

BBC: Watford boss Malky Mackay hopes to boost squad

Wednesday were partly the architects of the Hornets' first goal, failing to clear a corner and allowing substitute John Eustace to find Mariappa in the box with the simple task of tapping into the unguarded net.

BBC: SPORT | Football | Championship | Watford 4-1 Sheffield Wednesday