Messi scored the only goal of the match by converting a first-half penalty as the Albiceleste started their campaign with a gritty, if not entirely convincing, home victory at La Bombonera.
But the visitors equalized just after halftime through Pereira, who headed in his first goal of the season after a Diego Ribas set-piece.
"The players are finding their rhythm on the field, but they have yet to hit their best form to ensure a victory over South Korea next February," he said. "They need to further improve their techniques, coordination and tactics."
MADRID, Oct. 13 (Xinhua) -- Under normal circumstances Real Madrid forward Marco Asensio would be on international duty with Spain, but injury problems at the start of the season mean he will watch Tuesday's game against Ukraine from home.
The former Sao Paulo and Porto player praised his teammates for respecting their unfancied opponents.
According to Bayer Leverkusen, Arias suffered a fractured fibula and tore multiple ankle ligaments.
"Without doubt it's an important time in my career," Danilo, who has been capped 25 times, told a virtual news conference.
"I am not a doctor and cannot treat them, but maybe Tai Chi can help them improve rehabilitation."
Wu Tongtong got 21 points, Yu Dong scored 16 points while Zhao Zhifang added 13 for Shanxi.
Thepchaiya Un-Nooh and Anthony McGill both received a bye to the second round. Enditem
Murthy insisted that the club, which failed to qualify for Europe last season, has full confidence in Gracia to get the best out of the squad.