Ronaldo, one booking away from a suspension, was named among the substitutes on Saturday by coach Fernando Santos ahead of the crunch clash against Switzerland on Tuesday.
The second goal eventually came with five minutes to go, Andre Silva bundling in from close range after a left-wing Ronaldo cross was headed into his path by Danilo Pereira, with a straight shoot-out with Switzerland for top spot in Group B now set for Tuesday.
Portugal will next host Switzerland knowing that their superior goal difference means that only a win is needed to top Group B.
When asked about his decision to name Ronaldo on the bench, Santos told RTP: "I thought [about it] a lot". "Ronaldo didn't train at 100 per cent in the two days before the game". In 63rd minutes of the game, Ronaldo took control of the ball just outside of the box and took the lead of the game very carefully. But these games are complicated.
Belgium already qualified from Group H last month, and won 4-3 in Bosnia-Herzegovina to dent the home team's chance of claiming a playoffs place as one of the eight best runners-up in the nine European groups. Was it the right thing? A Selecção has secured at least a second-place finish but will be looking to overtake first-place Switzerland with wins in these last two games.
Santos had warned of the difficulties of facing Andorra, a physical, defensive side who play on an artificial pitch, which was in poor condition for Saturday's game.
"We knew it was going to be hard and it was notable the team had difficulties adapting to the pitch, and then with their defence very close, [we were] lacking momentum. We ended up winning as well, as we wanted," he said.
Along with him, Andre Silva also scored a winning goal so far. "We didn't do what we are capable of in the first half".
The Swiss lead Portugal in Group B by three points but have a vastly inferior goal difference, meaning a win for Portugal between the two sides in Lisbon on Tuesday will see them claim the automatic place for Russian Federation and Switzerland enter the playoffs.