Southend Utd 2 (Payne 4, Timlin 90+6)
Barnsley's six-match winning streak at home in the league came to a disappointing end as Southend took their time to a slender victory at Oakwell.
Conor Hourihane sent a penalty wide before the break as Barnsley wasted plenty of opportunities to level the tie against the professional Shrimpers.
With only four minutes on the watch Southend took advantage of a foul on Roberts that went unpunished to score the opening goal with the first shot of the match. Jack Payne wormed his way through into the box after Barnett held Roberts and poked home from eight yards.
Barnsley responded on nine minutes with Watkins charging into the box and seeing a shot blocked by Barrett with protests for a handball waved away by the referee.
A deep delivery by Hurst was met by Barnett on 15 minutes with Davies blocking well at his far post. Barnsley needed to find some form of rhythm. Still, Southend came at them and Payne flashed a shot wide via a slight deflection.
It should have been 2-0 as Wordsworth bent a delightful effort onto the bar with 20 played after being sent through by Payne on 20 minutes. Barnett then got a cross back in which Payne hammered over.
With 23 played the Reds were handed a lifeline when Fletcher was put through to be brought down by Bentley - the Southend 'keeper was shown a yellow card. Conor Hourihane stepped up but sent his penalty wide.
It summed up a frustrating first half for the Reds with the ball bobbling around and it seeming to break for the visitors every time.
On half-an-hour Alfie Mawson stung the gloves of Bentley with a dipping free-kick but the Southend stopper held it well at his top corner.
The Reds were being restricted to long-range efforts and although Brownhill did well to keep his shot under control it still rose up and over the bar after Hammill's delivery fell his way on 43 minutes.
In the first of two minutes added, a curling shot by Chapman seemed for a moment to be dipping into the top corner but Bentley pushed away for a corner.
It was evident the Reds were up for the second half but the visitors were taking their time with every throw to delay the Reds' efforts. However, good interchange between Brownhill, Chapman and Fletcher saw the latter upended on the edge of the box allowing Mawson the chance from the free-kick but the centre-half thumped the wall.
The Reds made the first change of the game with Harry Chapman being replaced by Sam Winnall on 56 minutes.
It should have been 1-1 on the hour as Brownhill cut through the middle of the park and sent Fletcher in, although the angle was tight he could still only prod straight at Bentley.
Again the Reds came forward this time with Hammill taking on two men and crossing for Watkins but he hammered his header into the side-netting with 25 left to play.
Winnall's first impact of the game came as he drew a block from White when Hourihane slipped him into the box. The head of steam was building but a goal was desperately needed.
It looked as though George Williams had picked up a knock and he had to be replaced by George Smith with 11 minutes remaining.
Barnsley's last change came on 87 minutes with Ashley Fletcher making way for Shaun Tuton.
With just over a minute of normal time to play, it appeared Sam Winnall's cracking drive from 25 yards was heading towards the top corner but it flashed just wide with Oakwell waiting for the net to bulge.
Five minutes of stoppage time was indicated by the Fourth Official for Barnsley to find the leveller.
Adam Davies prevented a Southend second on 92 minutes as he palmed over Payne's effort following a good counter by the forward.
In the sixth minute of stoppage time, the visitors took a break from slowing the play to score a brilliant second as Timlin rifled into the top corner to wrap up the points.
Reds: Davies, G. Williams (Smith 79), Connolly, Mawson, Roberts, Brownhill, Hourihane (c), Hammill, Chapman (Winnall 56), Fletcher (Tuton 87), Watkins.
Subs: Townsend, Nyatanga, Khan, Scowen.
Southend Utd: Bentley, White (c), Thompson, Barrett, Coker, Hurst (Atkinson 84), Kamara (Timlin 87), Deegan, Wordsworth (McLaughlin 69), Payne, Barnett.
Subs: Smith, O'Neill, McQueen, Loza.
Referee: Darren Handley.
Attendance: 9,903 (396 from Southend)