Barnsley stunned promotion favourites Watford 1-0 at Oakwell as Valerien Ismael made it two wins from as many games as head coach.
Alex Mowatt opened the scoring with a magnificent 25-yard strike in the fifth minute then the Reds held their own throughout the reminder of the match which saw both sides miss good chances.
The Reds are now 15th in the Championship and four points clear of the relegation zone.
Ismael chose Patrick Schmidt to replace the injured Cauley Woodrow in the middle of a front three while Matty James came back into the side for the benched Clarke Oduor.
Mowatt struck the opening goal from long range for the second Saturday in a row after doing the same at Millwall. This time his tremendous 25-yard effort hit the left post before going in.
The hosts could have doubled their lead but Dominik Frieser fired over from the edge of the box on 17 minutes after Conor Chaplin had volleyed the ball back to him from the right following superb work by Mowatt who turned a man and chipped a fine pass forward.
Another fine move eight minutes later saw Schmidt impressively flick the ball into the path of right wing-back Callum Brittain who cleverly pulled the ball back to the edge of the box where a sliding Chaplin sent a low shot straight at goalkeeper Ben Foster.
Watford did not have a shot or chance in the first half despite regularly finding space on the right side of the Barnsley box but lacking the end product.
Ismael took Brittain off at half-time and replaced him with Oduor who played at left wing-back with Styles moving to the right.
Watford began to create chances after the break, with former England international Tom Cleverley poking wide from seven yards out after a good run and pass by Sarr on the right.
Ben Wilmot then headed just wide of the top right corner from a right-wing corner.
Barnsley should have doubled their lead but George Miller – brought on for his second league appearance for the club more than a year after his first – fired wide of the bottom left corner after a lofted pass put him clean through on goal.
Wilmot then had another headed chance from a corner, this time from the left by Ken Sema, but he nodded into the ground and the ball again went just past the top right corner. That was the last chance of the match as the Reds held on for the three points against a side whose 18-man squad was recruited for £100million.
Barnsley (3-4-3): Walton; Sollbauer, Helik, Andersen; Brittain (Oduor HT), Mowatt, James (Kane 73mins), Styles; Frieser, Schmidt (Miller 59), Chaplin.Unused: Collins, Thomas, Simoes, Halme. Goals: Mowatt 5
Watford (3-5-2): Foster; Wilmot, Troost-Ekong (Gray 76mins), Cathcart; Femenia, Cleverley (Hughes 82), Capoue, Chalobah (Garner 66mins), Sema; Joao Pedro, SarrUnused: Bachmann, Ngakia, Kabasele, QuinaYellow cards: Troost-Ekong