Christian Pulisic's opener against Charlotte FC was cancelled out late on by a Daniel Rios penalty as the MLS side won the match after a penalty shoot-out in North Carolina.
Conor Gallagher missed the only spot kick to see Charlotte FC claim a 5-3 win in the shoot-out.
A severe weather warning saw the game kick-off an hour and five minutes later than originally planned, with both sides given the all clear to return to the pitch once thunder and lightning had come to a halt.
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The Blues opted for near to two different sides, with Edouard Mendy the only player to play the whole match.
Chelsea started the game on top, dictating the tempo with a quick passing game before Callum Hudson-Odoi, playing at right wing-back, fired a low shot just wide on the five minute mark.
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Just minutes later a nice bit of play saw Mateo Kovacic combine well with Michy Batshuayi, with the Croatian firing into his former Dinamo Zagreb teammate Kristijan Kahlina's arms.
However, it was Charlotte FC who should have been ahead as Christian Fuchs picked out Karol Swiderski with a fine cross, but the forward headed down, with Edouard Mendy saving the shot.
Moments later, Yordy Reyna struck the post for Charlotte FC with a fantastic curling shot from the left side of the box, but the offside flag was up.
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Chelsea were in front 30 minutes in through Pulisic, who ran onto a deflected Batshuayi shot before chipping over the onrushing goalkeeper to put the Blues ahead.
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Batshuayi should have doubled Chelsea's lead five minutes later, running onto a Jorginho pass before taking a touch around a Charlotte FC defender in the box before seeing his low shot saved by Kahlina's right boot.
Thomas Tuchel's side went into the break with a 1-0 lead, despite Charlotte FC having several chances to level the scoreline.
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The second period saw 10 changes as Mendy was the only player to remain, with Raheem Sterling on for his first appearance in a Chelsea shirt.
Ethan Ampadu had the first chance of the second half, playing in central midfield. The Welsh international did brilliantly to flick the ball over the head of a Charlotte player, before closing down a loose ball and seeing a clearance strike him, forcing the goalkeeper into action to push over the bar.
Sterling looked sharp since coming onto the pitch at the half and was unlucky not to get on the end of a Gallagher cross.
A few minutes later the England winger showed his class, drawing a foul as on the right hand-side of the Charlotte FC box, with Mason Mount firing over the resulting free-kick.
The hosts should have been level in the 65th minute Rios could not get onto the end of a Kerwin Vargas deflected cross, with the goal at his mercy.
A few moments later, Malang Sarr saw his header saved from George Marks, firing straight at the goalkeeper from a Ben Chilwell corner.
A clever bit of play in the 74th minute saw Sterling find Mount, who played a chipped ball to Kenedy on the right. The Brazilian picked out Mount once more with a clever outside of the foot pass before Mount fired at Marks in the Charlotte FC goal.
The Blues began to get more luck down the right, with Ampadu picking out Kenedy, who cut back to Gallagher. The England international released a weak shot into the hands of the Charlotte FC goalkeeper as Chelsea searched for a second goal.
With just over 10 minutes to go, Chelsea were let off as Andre Shinyashiki missed a glorious chance, being gifted a free header from a corner.
In the dying moments of the game, Charlotte FC were gifted a penalty as Trevoh Chalobah was penalised for a handball, with the ball striking the defender as he dived in to block a shot.
Rios converted from the spot, with the final kick of the game as the match headed to penalties.
Scoring the first penalty of the shoot-out moments after he bagged in the match, Rios set the tempo as he scored a panenka to get the ball rolling.
The MLS side came out victorious in the shoot-out, with Gallagher missing his penalty as the hosts won 5-3 in the shoot-out.
Topics: Chelsea, Football, Christian Pulisic, Raheem Sterling
Nick Emms