TEENAGER Tyler Roberts scored the deciding penalty as Oxford United progressed to the third round of the Checkatrade Trophy.

The U’s had lost both their shoot-outs in the competition’s group phase, but only Marvin Johnson failed to score at Roots Hall as Simon Eastwood saved from Simon Cox and Stephen McLaughlin fired over.

Chris Maguire’s 30-yard free-kick late on had appeared to send Michael Appleton’s side through without the need for spot kicks.

Anthony Wordsworth quickly equalised, but the visitors – who had lost on seven of their last eight visits to Southend – shrugged off the disappointment to reach the last-16.

Skipper John Lundstram and fit-again Curtis Nelson were among six players brought into the side from Friday’s goalless draw at Macclesfield Town.

Head coach Appleton also changed his front two, who combined in the sixth minute to create the clearest chance of the half.

Kane Hemmings did well to turn a hopeful Lundstram ball over the top into something threatening, getting the better of two defenders before cutting the ball back to Ryan Taylor.

The striker was unmarked ten yards out, but shot straight at Mark Oxley.

A relieved Southend goalkeeper made the block, as he did again a minute later to keep out a long-range effort from Maguire.

Ryan Leonard had earlier headed a corner just wide, in what was the closest Southend came in the opening half-hour.

The small crowd at Roots Hall had little to get excited about in a largely uninspiring spell before the break.

U’s goalkeeper Eastwood was stretched only once, palming away a curled 20-yard effort from Wordsworth in the 35th minute.

At the other end Taylor was again thwarted by Oxley, this time from 25 yards out.

Wordsworth hit the outside of Eastwood’s left-hand post with a bouncing effort from the edge of the box a minute into the second half, but from then on the U’s enjoyed a good spell.

A Phil Edwards shot swerved inches wide, before Oxley made another good save to keep out Maguire’s 15-yard volley.

Southend’s threat was sporadic, but they still gave the U’s some nervy moments.

Cox’s powerful header on the hour was ruled out for offside, while Eastwood just got fingertips on the ball to deny McLaughlin after the wide man beat Edwards.

A penalty shoot-out was looming, but nine minutes Maguire came up trumps with an exquisite free-kick.

United could not see out the game, though, and in the 86th minute Wordsworth tapped in substitute Marc-Antoine Fortune’s low cross from a couple of yards out.

It ensured an extension beyond the final whistle, but 17-year-old substitute Roberts sealed the victory.

Southend Utd (4-4-2): Oxley, Demetriou, Ferdinand, Thompson, Timlin, Atkinson (O’Neill 54), Wordsworth, Leonard, McLaughlin, Ranger (Fortune 78), Cox.

Unused subs: Smith, White, Sokolik, King, McGlashan.

Booked: Timlin.

Oxford Utd (4-4-2): Eastwood, Edwards, Nelson, Martin, Johnson, Hall, Lundstram, Ruffels, Maguire, Hemmings, Taylor.

Subs used: T Roberts (Hall 78).

Unused subs: Buchel, Carroll, Welch-Hayes, Dunkley, Ledson, Rothwell.

Booked: Ruffels, Taylor.

Referee: Trevor Kettle (Leicestershire).

Attendance: 2,004 (88 visitors).