Declan Rice and Kai Havertz make mark as Arsenal crush MLS All-Stars
Rice became the most expensive British player in history when Arsenal signed the England midfielder from West Ham for a reported £105 million.
The England international was introduced from the bench in the 65th minute to huge cheers from the overwhelmingly Arsenal-supporting crowd.
German Havertz, who joined Arsenal from London rivals Chelsea last month, was brought on after half-time and grabbed the fifth goal in the 89th minute.
The Premier League runners-up, began their pre-season tour of the United States, in style with Gabriel Jesus's brilliant chip in the fifth minute.
The move began with a smart ball out wide from Jorginho to Bukayo Saka and after he burst inside the ball fell to Jesus who took one glance and lofted the ball in off the far post.
There was an opening for the MLS team, coached by D.C. United manager Wayne Rooney, to get a quick reply but former Liverpool forward Christian Benteke mis-controlled the ball inside the box.
Saka had a hand in Arsenal's second goal, in the 23rd minute, bursting down the right and then picking out Leandro Trossard who created himself some space before firing home a superb strike.
Rooney said he hadn't had time to do any tactical work with his team, made up of players from across the North American league, and it showed as Arsenal totally dominated.
Rooney made five changes at the interval but any hopes of a comeback ended quickly when one of those subs, St. Louis City defender Tim Parker, handled at close range an attempted cross from Jesus.
It was a harsh decision but Jorginho made no mistake from the spot to make it 3-0.
There was some concern for Arteta when Trossard limped off with an injury but the man who replaced him, Gabriel Martinelli, made an impact, scoring the fourth.
Martin Odegaard ripped open the MLS defence with a sweeping ball out to the Brazilian winger, who burst goalwards before burying his shot in the far, bottom corner.
Havertz rounded off the win in the final minute, chesting down a Marquinhos cross and confidently drilling home.
Saka said the new faces had made a swift impact on the team.
"I think we showed in glimpses how well we can play. I'm really happy with the new signings, how they got on as well and gelled with the team," he told broadcasters Apple TV.
Arsenal will now travel to New Jersey to face Premier League rivals Manchester United at MetLife Stadium before taking on Spanish giants Barcelona in Los Angeles.