Reigning UEFA Nations League champions Portugal needed less than six minutes to break the deadlock through the diminutive Joao Neves, who supplied a precise header from a nice Pedro Neto cross for his fourth goal in his last two competitive internationals.
That looked as though it might set the tone, but the Leopards mustered a decent immediate response, with Yoane Wissa flashing an effort narrowly wide before Cedric Bakambu saw an effort blocked.
Adding Bruno Fernandes to two-thirds of the Paris Saint-Germain midfield was always going to lead to a chance or two for Portugal at the other end, and the Manchester United man found a lovely pass to set Nuno Mendes free, requiring a good stop from Lionel Mpasi to keep the deficit down to one.
But even with the impressive array of playmakers on show, Portugal struggled to fashion any more clear-cut openings, as DR Congo stuck admirably to their defensive game plan despite conceding the early goal.
And that paid off on the brink of half time, as Wissa was left in glorious isolation from a corner to head beyond a helpless Diogo Costa for his country’s first-ever WC goal. The African side saw just 20% of the ball in the first period, but ultimately merited their equaliser.
After Portugal mustered just two shots in the first half, Francisco Conceicao replaced Bernardo Silva at the break, and he had the first chance of the second period, losing a battle of strength at the far post as he looked to connect with a cross from the left.
Joao Cancelo then looked to have restored Portugal’s lead in acrobatic fashion, hooking a chested Neves pass beyond Mpasi, but the offside flag went straight up.
DR Congo still posed a threat of their own, and Bakambu gave Portugal a scare when he rattled the post, although the referee ultimately brought it back anyway for a foul on Fernandes.
At the other end, Cristiano Ronaldo finally got his first sniff at goal, but couldn’t quite adjust sufficiently to divert Conceicao’s pass into the corner.
The game began to open up a little in the closing stages, but half-chances for Bakambu and Cancelo at either end came to nothing, and the contest ended all square.
For the Leopards, this is already an improvement on their last WC appearance, when they conceded 14 goals without reply across three defeats.
This time around, they have given themselves every reason to be optimistic of progressing from Group K, with Uzbekistan and Colombia set to face off later on in the other opening fixture.
Portugal will hope to quickly fix their surprisingly blunt-looking attack, with Ronaldo made to wait for a goal at a sixth different edition of the WC.
Flashscore Man of the Match: Joao Neves (Portugal)