Monaco boss Leonardo Jardim's return to the Estadio Jose Alvalade ended in a 2-1 friendly defeat to former club Sporting CP.
Jardim swapped Lisbon for Monaco in 2014 and his Ligue 1 champions were beaten by first-half goals from Bruno Fernandes and Bas Dost in the Portuguese capital.
Monaco named a strong line-up that included starts for in-demand teenage sensation Kylian Mbappe and promising midfielder Thomas Lemar, but Benjamin Mendy - linked with a move to Manchester City - was left out of the squad along with former Sporting player Joao Moutinho.
Dost, the subject of interest from Newcastle United earlier in the transfer window, set up Fernandes' opener before adding a towering header, with substitute Guido Carrillo's stoppage-time strike providing the visitors with a consolation.
Rui Patricio gifted Monaco in the eighth minute when he kicked the ball straight to Lemar, but the goalkeeper's blushes were spared by Sebastian Coates, who blocked Mbappe's effort on the line after Radamel Falcao's initial shot deflected to France forward's feet.
Monaco thought they had taken the lead when Rony Lopes fired a sensational effort home from just outside the box after a corner, but Terence Kongolo was deemed to have obscured Patricio's view and was adjudged offside.
The Ligue 1 champions were behind in the 32nd minute, though. Gelson Martins surged through the middle and fed Dost, whose scuffed shot across goal was turned home from an acute angle by Fernandes.
Dost got on the scoreboard himself three minutes before half-time, climbing above Kamil Glik to head a corner by Marcos Acuna - who sent a free-kick narrowly wide earlier in the half - into the top-left corner.
Sporting changed kit for the second half and their line-ups soon followed suit, with Portugal internationals Adrien Silva and William Carvalho introduced for sporting while Falcao and Mbappe made way for the visitors.
Carrillo had a looping header clawed out of the top-right corner by Patricio, but got on the scoresheet in added time, punishing a lapse of concentration in the Sporting defence by slotting home - though it was too late for a draw to be salvaged.