De Ligt's Ajax had to settle for a draw in the first leg of the quarter-final tie despite dominating in Amsterdam, where Ronaldo's opener was cancelled out by David Neres on Wednesday. There is good reason to think we can get to the semi-finals.
Year after year the 34-year-old has produced when his team need him most. "We've done well so far in the Champions League, and we're not done yet", said the midfielder Frenkie de Jong, who was outstanding.
The visitors had the first attempt when Federico Bernardeschi smashed over the bar in the second minute, but Ajax had most of the better chances. His goalscoring return was naturally the subject of the Thursday headlines in the Italian media, with local paper TuttoSport leading their front page with the words "Juve flying with Ronaldo". Juventus almost won it when Douglas Costa hit the post in the 85th.
The second leg is scheduled for next Tuesday in Turin, with the victor to face Manchester City or Tottenham in the semifinals.
SPAL, 16th and just four points above the drop zone, had eased their relegation fears with three consecutive wins that included victories over Champions League-chasing Lazio and Roma, but lost last weekend at Cagliari.
"We knew we had to bring that intensity that they're not used to".
In the previous round, Ronaldo nearly single-handedly overturned a 2-0 first-leg deficit to Atletico by scoring a hat trick in a 3-0 win.
"The whole team, we nullified them".
It's for that reason that Valverde has opted to leave his star players at home to ensure they are fully fit and ready to complete the job against Ole Gunnar Solskjaer's men next week.
"We have to examine him tomorrow to see how he is. The draw is a result, which allows us to have a better position for the away game".
He scored his 125th through a stylish diving header that beat Ajax goalkeeper Andre Onanana, thanks to Joao Cancelo's sublime assist. "He sprints into the area between two players".
"Ronaldo showed that he is on a different level".
Remarkably, it means only Messi - with 108 - is within 50 goals of the Portuguese great when it comes to Champions League goals.
He is now 17 goals ahead of his nearest rival Lionel Messi.
Ronaldo's Juventus are in action against SPAL today (2pm).
The goal - initially flagged for offside before being awarded via a video review - came in the 12th minute during an exhilarating spell when Barcelona's possession exceeded 80 per cent at Old Trafford.
Twitter user Grant Evans said: "Ronaldo is a complete class act!"