The on-loan Sporting Lisbon winger scored with a fine finish in the 2-1 win over Shelbourne on Wednesday night.
Monk has been busy already in the transfer window this summer, signing six players already in a variety of positions, and three of those new faces started for the Whites.
Loanees Kyle Bartley and Hadi Sacko were given the nod along with midfielder Kemar Roofe, and it did not take the new boys too long to make an impact as Leeds raced into an early 2-0 lead.
First Roofe charged down an attempted clearance, allowing Souleymane Doukara to fire home, and then on-loan Sporting Lisbon winger Sacko capped off a nice move by finishing neatly from Alex Mowatt's pass.
Though Shelbourne pulled one back shortly after the break, Leeds held out for the win, and Sacko took to social media on Thursday afternoon to react after making a scoring start to life at Elland Road.
On his personal Instagram account, Sacko wrote: "Happy to get our 1st friendly game under our belts #LUFC #MOT"
Monk will surely be pleased with what he saw from Sacko and the rest of his players as he looks to build a squad capable of finally launching a serious play-off challenge this term.
After the likes of Sacko, Roofe, and Mowatt had impressed, the new Whites boss made 11 changes on the hour mark, bringing players including newly-signed pair Marcus Antonsson and Matt Grimes.
Antonsson looked lively on his first appearance, testing the goalkeeper with a couple of efforts and showing good movement in attack, and all in all it was an encouraging start for the new players and manager.