Turns out, there was more than one confused world leader at the ASEAN summit photo op.
Take a closer look at Russian Prime Minister Dmitry Medvedev on the left.
The concept of the traditional crossover handshake for the ASEAN 'family' photo is pretty straightforward.
Each leader crosses his or her arms and join hands with the world leaders on either side.
And while almost all the politicians on stage managed to reach out and clutch the hands of the person to their left and right, both Mr Trump and Mr Medvedev didn't.
That left ASEAN summit host Philippine President Rodrigo Duterte with a spare hand - and broke the line into two parts. Awkward.
And while it took more than a few seconds for him to recognise his error, Mr Trump finally made the link between Mr Nguyen and Mr Duterte.
The Russian PM, on the other hand, simply didn't.
Whether Mr Medvedev's handshake gaffe was deliberate or accidental remains unclear. But pictures show the Russian leader smiling widely with his arms outstretched, despite his faux-pas. Twitter eventually caught on to the goof-up and had a good laugh.
The official #Asean2017 handshake. Link almost failed to connect, but #POTUS#DonaldTrump used his felxibility skills while #Russian PM #Medvedev took a shortcut by not crossing his arms. #aseanmomentspic.twitter.com/1JMY8SP5If— Karen Jimeno (@AttyKarenJimeno) November 13, 2017
Looks like Trump beat Medvedev in the ASEAN handshake game at least. https://t.co/jYu4FbZk17— Adam Taylor (@mradamtaylor) November 13, 2017
Is that Medvedev who isn't playing along and, actually, emerges as the winner? https://t.co/1zBIXcLjz7— David Nakamura (@DavidNakamura) November 13, 2017
Looks like Russian Prime Minister Medvedev (2nd from left) has it all figured out! pic.twitter.com/NlPOwd2yrT— Tony Valentino (@tonyv561) November 13, 2017
Mr Trump's handshakes with world leaders frequently make headlines and Monday's incident at the ASEAN summit brought back memories of previous awkward encounters. Click for more trending news