Mexican teenager Carlos Vela came off the bench to inspire Arsene Wenger's young Gunners to a 2-0 Carling Cup victory over 10-man West Brom at the Emirates Stadium.
The 20-year-old marked his return from an ankle injury when his shot set up Sanchez Watt for the opener in the 68th minute and then added a tap-in after Mark Randall's clever chip came back off the crossbar.
After a positive start the Coca-Cola Championship leaders were up against it after former Gunner Jerome Thomas — who twice won the FA Youth Cup while at Arsenal — was sent off after 37 minutes for a completely needless slap on Jack Wilshere.
Wenger had once again given youth a chance, his team with an average age of just over 20, while also bringing in experienced defender Philippe Senderos and veteran Mikael Silvestre captained the side.
Senderos had an early chance when he headed over at the near post following a corner from the left.
With Watt and French teenager Gilles Sunu Arsenal certainly had plenty of pace in attack, while Wilshere and Aaron Ramsey — both with plenty of first-team experience already — provided the trademark quick passing through the midfield.
Polish goalkeeper Wojciech Szczesny, 19, made the first meaningful contribution on his debut when punching a corner clear at the near post and he was stretching in the 15th minute as Robert Koren's angled 20-yard drive flew just wide.
Watt came within inches of opening his Arsenal account when he stabbed Wilshere's cutback goalwards, only for the ball to bounce agonisingly off the inside of the post and into Dean Kiely's grateful arms.
West Brom swung a free-kick into the area which Szczesny dropped under pressure at the far post from Leon Barnett, but fortunately Kieran Gibbs — who had played in the Champions League semi-final defeat to Manchester United last season — was on hand to clear.
West Brom continued to look dangerous on the break, with Thomas' run down the left forcing Szczesny to make an important block.
However, the 26-year-old was shown a straight red card in the 37th minute after he clashed with Wilshere, before then slapping the midfielder in the face while he was on the floor.
Cox also went into referee Lee Mason's book for his protests.
Cox headed over for the first real chance of the second half when well placed in the six-yard box before Wenger made a change in the 58th minute.
It took a moment of Premier League quality from Vela to finally help break the deadlock.
The 19-year-old showed great close control to create space for a shot from the edge of the penalty area, which Kiely palmed wide, and Watt followed up to smash in his first senior Arsenal goal.
The Mexican then got the goal he deserved after 75 minutes.
Randall's 20-yard chip came back off the underside of the bar — and Vela was alert enough to get in between Barnett and Kiely before knocking the ball over the line.