Barnsley 1 (Gray 58)
Watford 1 (Sordell 37)
The 9,186 Reds fans were delighted with another great performance from their side, who only managed a point despite their dominance throughout the 90.
Andy Gray grabbed the leveller on 58 minutes with a wonderful header - meeting O'Brien's brilliant right-wing delivery, after Marvin Sordell's tap-in opened the scoring on 37.
An injury in the warm-up to Haynes meant Cameron Park made his debut down the right after his loan move from Middlesbrough - Alastair Taylor was promoted to the bench.
Park had an immediate impact down the right and the Reds had struck the post inside a minute. Perkins it was with the effort, the ball striking the back of Loach and out for a corner after his side-footed 20-yard effort hammered the upright.
A Yeates cross was the closest the Hornets came to an opener on eight minutes - his delivery was begging to be turned home but no yellow shirt arrived.
Watford countered after another great Barnsley move involving O'Brien and McEveley down the left - but a quick break saw Weimann strike wide from 20-yards on 10 minutes.
Hassell whipped in a delicious ball to the near post on 14 where Gray almost got in but was denied by a terrific challenge from Taylor. That move really sparked more confidence in the Tykes and several more efforts on goal followed with strikes from Butterfield, Drinkwater and Perkins all going close.
The Reds were really taking the game to Watford - who were having to rely on the counter-attack. Drinkwater dished the ball out to Park, whose pass to Gray was eventually laid off for Butterfield to hammer over on the half hour mark.
Again Butterfield was in the thick of it inside a minute later - the midfielder scooping over from close-range. Drinkwater set the move going for O'Brien, who wormed his way into the area before pulling back for Butterfield who just couldn't keep it down from inside the six-yard box.
In the 37th minute Watford took the lead out of nowhere after some sloppy Reds defending. Marvin Sordell had the simplest of tasks to tap home Yeates' nod back at the far post.
The Reds did respond after Watford had taken the shock lead, Perkins blasted one towards goal that deflected out for a corner, and from the resulting set-piece Foster's header hit his own man McNulty to add to the Reds' frustration.
Watford's Loach got down low to deny a powerful Butterfield drive in the 47th minute, the Reds were looking to start the second period as they finished the first. Four minutes later, and unsurprisingly it was Butterfield who was at the end of another neat Reds move. The former Manchester United man curled wide with the right peg after Drinkwater's lay-off on the edge of the area.
Two minutes before the hour mark and Barnsley hauled themselves back into it after a phenomenal cross from O'Brien found the head of Gray. Perkins sprayed the ball out to the right for O'Brien, whose delivery would have found the flee on a dog's back, thankfully it was Gray on the end of it - hammering his header into the roof of the net off the turf.
Some wonderful flowing football from the Reds was causing pandemonium in the Watford area, O'Brien's through-ball down the right on 67 found the steaming run of Hassell, after cutting in on his left, he could only curl over Loach's bar.
Vaz Te was thrown on for Park down the left-wing, as Watford made use of their final two subs, Iwelumo and Garner coming on for Weimann and Sordell in attack with 15 to go.
With little action over the next five minutes, Doyle replaced Drinwkater in the middle to sure up the Barnsley engine. Despite the Tykes still bossing the pace of play, Steele was still involved - doing well to stop Forsyth's wicked left-foot volley from 20 yards.
Two corners at the death for the Reds almost allowed McNulty to power a header in, but for a wonderful block in the air.
Reds: Steele, Hassell, McEveley, Foster, O'Brien, Park (Vaz Te 76), Perkins, McNulty, Butterfield (c), Drinkwater (Doyle 84), Gray.
Subs: Preece, Wiseman, Taylor.
Watford: Loach, Dickinson, Eustace, Taylor, Mariappa, Yeates (Deeney 65), Forsyth, Doyley, Weimann (Garner 75), Sordell (Iwelumo 75), Hogg
Subs: Gilmartin, Mirfin.
Attendance: 9,733 (547 away)