Thrilling maiden victory for Team Novadriver Portuguese pair
The Russian Esta Motorsports Ferraris, benefitting from home advantage, were second and third with the No.199 car of Aleksy Basov (RUS) and Bjorn Grossman (DEU) leading home the No.177 of Aleksander Skryabin (RUS) and Alessandro Pier Guidi (ITA).
Amorim and Campanico, who had a third place finish in Navarra and a second in the previous round in Portugal, continued their upward trend in trying conditions.
"This was a very good weekend for the team. It was very difficult conditions today, a little dangerous maybe, but we came through," Amorim said.
"We had third place in Navarra, second at home in Portimao and here we are first. It is nice to finally get a win today," Amorim said.
Germany's Grossman was delighted to help give home fans something to cheer about by leading home the Esta Motorsports two-three finish in the No.199 Ferrari 458 Italia.
"It was a good result for the team. It was the first FIA GT3 race we have done and for me my first time here and in a GT3 car so it's an amazing result to end the weekend in this perfect way," he said.
Skryabin, who had challenged for the lead and eventually surrendered second place with a spin towards the end, was happy with third nonetheless. "I am really happy to be on the podium. It is nice for the Russian fans who came here in such bad weather. This team result is for them," he said.
Heavy rain before the start rendered track conditions treacherous and like Race One earlier in the day, the GT3 field lined up behind the Safety Car for the start.
The Safety Car departed but was redeployed after just four laps as visibility became a problem due to the standing water on the track.
Once the pack was released, the No.101 Heico Gravity-Charouz Mercedes of Dominik Baumann (AUT) and Maximilian Buhk (DEU), the Race One winners, led the way.
The drivers' championship leaders looked set to add a second race win to their weekend's haul before eventually finishing fifth after tyre performance drop-off hindered their efforts.
Championship challengers in the Rhino's Leipert Motorsport Lamborghini Hari Proczyk (AUT) and David Mengesdorf (DEU), who had finished second in Race One, retired after three laps with accident damage.
Baumann and Buhk still have a grip on the drivers' championship with 164 points. Michael Lyons (GBR) and Stefano Gai (ITA), fourth today in the AF Corse Ferrari, move up to second on 128 points ahead of Hari Proczyk and Mengesdorf (127).
Gaetano Ardagna Perez (VEN) and Giuesppe Ciro (ITA), second overall before the Moscow weekend, drop to fourth on 125 after a Race Two retirement. They failed to add to their third place finish in Race One.
In the teams' standings, AF Corse lead on 295 points, from Heico Gravity-Charouz (286) and Rhino's Leipert Motorsport (153).
The sixth round of the championship takes place at Nurburgring on 21-23 September.