The match was a repeat of last season's quarter-final which Juve won 3-0 on aggregate, but it was Barcelona who prevailed by that scoreline on matchday one as Messi continued his inspired early-season form.
"They have lost Bonucci but they remain a very strong, good team", said Valverde on Monday.
But, with half-time looming, Juventus committed the fatal error of switching off while Messi had the ball on the edge of the box. A millisecond later, the ball struck the inside netting. It might be tempting to pencil in the two super clubs as the obvious teams to advance, but one dominating the other could open the door for an upset.
Neymar was the first on the scoresheet, nabbing his fifth goal in as many matches for PSG by beating his man on the counter and blasting a shot past the keeper for the 1-0 lead.
Andres Iniesta, starting his fourth game in little over a week, shimmered. Let's see how they fared in their respective matches.
Two woefully uncompetitive games saw Paris Saint-Germain and Bayern Munich post easy wins.
The German pulled off a fine save to deny Mattia Di Sciglio's long range effort.
There had been speculations this summer about Paulo Dybala's move to FC Barcelona.
Reuters/Sergio PerezBarcelona's Lionel Messi celebrates after he scored their first goal against Deportivo Alaves, May 27, 2017.