McKennie, Pepi double as US thrash Grenada 7-1
Chelsea's Christian Pulisic, Leeds forward Brenden Aaronson and Alejandro Zendejas also scored for the US, who were playing their first competitive fixture under interim coach Anthony Hudson.
The build-up to the game had been dominated by the fallout from the World Cup controversy surrounding US forward Gio Reyna, handed a start by Hudson for Friday's game at the Kirani James National Stadium in St. George.
However, Reyna endured a frustrating night, contributing little of note to the US performance before being substituted midway through the second half.
The Americans effectively wrapped up victory after a dominant opening 45 minutes that saw them take a 4-1 lead at half-time.
Netherlands-based striker Pepi, earning a start after missing out on a place in the US World Cup squad, opened the scoring after just four minutes.
Pulisic crossed from the left and Pepi was on hand to direct a firm glancing header into the Grenada net.
The US were given a scare moments later though when only a fine diving save from Arsenal's Matt Turner denied Jacob Berkeley-Agyepong an equalizer, the American goalkeeper tipping the London-born forward's low shot onto the post.
Pepi almost doubled the US lead on 13 minutes, but saw his shot saved from close range by Grenada goalkeeper Jason Belfon.
The US did not have to wait too long for their second goal however, with Pulisic again the creator, passing low to Leeds forward Brenden Aaronson who danced past his marker before rifling a low shot into the bottom corner.
McKennie added a third on 31 minutes, hooking in a volley after a Pulisic free-kick sowed panic in the Grenada defence.
Grenada hit back almost immediately with Myles Hippolyte – who plays in the fourth tier of English football for Stockport County – lashing home from the edge of the area.
But any hopes of an unlikely Grenada fightback were snuffed out within minutes, when McKennie grabbed his second.
Pulisic's free-kick was headed back across the six-yard area by Auston Trusty for McKennie who stabbed home from close range for 4-1.
The goals continued to fly in after half-time.
Pulisic made it 5-1 on 49 minutes when his low shot squirted under Belfon and into the net, before Pepi added his second after collecting Luca de la Torre's pass and whipping a finish in at the near post.
Zendejas, who replaced Pulisic on 64 minutes, made it 7-1 in the 72nd minute, coolly bending a low shot into the bottom corner from the edge of the area after being given time and space to pick his spot.
The victory means the USA need only a point against El Salvador at home on Monday to assure themselves of a place in the final four of the CONCACAF Nations League in June.