A completely mixed-up Arsenal side defeated West Ham United in the quarter finals of the League Cup at the Emirates on Tuesday night, with Danny Welbeck’s first half strike proving the difference between the sides.With a huge league meeting against Liverpool only 72 hours away from kick-off of this match, Arsenal manager Arsene Wenger rang the changes, fielding a team with no members of the side who dispatched Newcastle United in the league on Saturday.In an effort to secure passage to the Semi-Final of a trophy that has avoided him, Wenger opted for experienced fringe players sprinkled with a couple of promising younger players, with midfielder Jo Willock starting the game along with centre backs Calum Chambers and Rob Holding in what was a traditional 4-4-3. Up front, the returning Theo Walcott was joined by Olivier Giroud – who left the pitch with an injury - and Danny Welbeck, who’s 42nd minute finish was the only goal of the game, ensuring the Gunners remain in all competitions they are involved with into the New Year. Giroud’s injury, along with fellow starter Francis Coquelin who also had to leave the field, becomes all the more frustrating considering how congested the coming weeks are for Wenger’s side, but nonetheless, at least the win was secured.The game began very slowly, perhaps a sign of two sides with the weekends fixtures on their minds – West Ham are visited by Newcastle in a huge game for both clubs on Saturday – but towards the end of the half Arsenal began putting the pressure on in what ultimately resulted in the game’s only goal.Just minutes prior to Welbeck finding the net, full back Sead Kolasinac went on a run down the left wing, stretching the Hammers defence, and delivering a cross that evaded all defending to find Walcott free close to the penalty spot, with his diving header floating wide of the post, the dismay of those attending the game. Thankfully, just a few minutes later, the ball had found its way past the re-instated Joe Hart’s net. Coquelin chipped a ball to the right of the field, and Mathieu Debuchy found himself in an advanced position, delivering the ball first time with his head into the opposition area. Welbeck leapt up while attempting to put a shot in, but was restricted by the presence of James Collins and Winston Reid – although when the ball landed from the tangle of bodies, it fell kindly, allowing the Englishman to bundle the ball (not all that cleanly) by Hart. They all count.And Arsenal went in at half-time deservedly in front – not because they were particularly good, but because they were definitely the side that were playing for it the most, which was heartening to see.7,000 West Ham supporters made the trip across London for the game, and they will have seen 5 of the players utilised in the win against Stoke City at the weekend in action. David Moyes’ side don’t have the resources of Arsenal, which was plain to see, but they still gave some youngsters a chance, including 18 Year Olds Irishman Declan Rice and also a first professional start for former Chelsea Youth player Domingos Quina, both in midfield.The second half mirrored much of the first in that West Ham didn’t particularly offer a lot, and with a lead, Arsenal were allowed to control the game. Amusingly, an Aaron Cresswell free-kick was met with audible chants of “we’ve had a shot!!” mid-way through the second half. It summed up the game in many ways for West Ham, with the side definitely more focused on continuing their impressive league form with 7 points from the last 9. In a last throw of the dice, Andy Carroll was brought on, with Moyes changing his tactics to a more direct approach. In ways it worked, in that the appeared more dangerous, but they did not threaten for an equalizer.During the second half, more young Arsenal players were introduced. Reiss Nelson was brought on for the injured Giroud in the 78th minute; Ben Sheaf replaced Jo Willock from the 84th minute; and Josh Da Silva came on late after Coquelin required treatment following a clash during an aerial duel with Carroll. While none of the young subs had a particularly long amount of time on the field, it is good to see some fresh blood being introduced in cup competitions.The full-time whistle blew, and Wenger had arrived in the semi-final of what has been an elusive domestic trophy for the veteran Frenchman.Arsenal will be joined in the semi-finals by Manchester City, who beat Leicester City on penalties following a very, very late Jamie Vardy equalizer to make it 1-1; and the winners of Bristol City vs Manchester United and Chelsea vs Bournemouth, who play on Wednesday night.Attention now return to the Premier League and an enormous match-up against fourth place Liverpool at the Emirates on Friday night. It is unlikely that any of the players who featured tonight will begin the game against Jurgen Klopp’s side, although Wenger may choose to retain Kolasinac, Mohamed Elneny, Walcott or potentially even match-winner Danny Welbeck.Those who played at the weekend will surely be well-rested for Friday’s match, and while it was terrific to get the win tonight and progress in the tournament, one can only hope that the injuries to Giroud and Coquelin aren’t bad – with this many upcoming fixtures in such a short space of time (10 in the next 36 days), the side need all of the fit players they can get.