Philippe Coutinho has urged patience from Brazil following the favourite's uneven start to the World Cup and the latest hysteria surrounding Neymar's fitness ahead of Friday's match against Costa Rica in St Petersburg.
The world's most expensive player scored Brazil's second stoppage-time goal and was in tears at the full-time whistle.
A dogged defensive display forced Brazil to wait until the 91st minute for Coutinho to find the breakthrough, although Costa Rica crafted a few chances of their own - leaving Ruiz to wonder what might have been.
Neymar thought he had a penalty with 13 minutes remaining when the referee awarded a spot-kick, then changed his decision after a video assistant referee (VAR) review and adjudging he dived.
In another Group E fixture at Saint Petersburg, Brazil sealed a 2-0 win over Costa Rica.More news: Mohamed Salah considering retirement over political controversy with Chechen leader
The Brazil star missed Monday's training, the day after he was fouled 10 times during a 1-1 Group E draw with Switzerland.
The forward came in for criticism after Brazil's 1-1 draw with Switzerland in the nation's World Cup opener and was well below his best against Costa Rica.
Between Alisson and Keylor Navas, the latter had a busy night parrying shots from the non-stop Brazilian pressure.
Neymar's emotions at the end highlighted Brazil's relief at getting their first win of the tournament after being held 1-1 by Switzerland in their opening match. "The second half, it was attractive, perfect".
"Messi is very good, but it is clear that he is very good because he is surrounded by extraordinary players (at Barcelona)", said Simeone, who now manages Atletico Madrid.More news: Brigitte Nielsen Gives Birth to Baby Girl
Let's face it, Serbia have been playing an excellent game of soccer so far in the World Cup Group Stages and if they do not make it through to the next round something has gone seriously wrong!
Nigeria's pace and solid defending were enough to beat Iceland 2-0, with a double from Ahmed Musa.
Brazil's next game is against Serbia on Wednesday. They had met previously on 13 occasions when Serbia was a part of Yugoslavia.
Aleksandar Mitrovic gave Serbia the flawless start after five minutes, but the Swiss gradually worked their work back into the game in rainy Kaliningrad.
Costa Rica made their first switch, replacing Urena with Christian Bolanos before, after 57 minutes, Brazil were foiled again when Navas superbly tipped over Neymar's crisp strike.More news: Mexico fans celebrate second consecutive win in World Cup
The competition's most decorated nation were in danger of failing to win either of their first two games in Russian Federation before Coutinho prodded in a stoppage-time opener and Neymar added a second in a 2-0 success.