Ryan Gosling paid a late-night visit to ladylove Eva Mendes' Los Angeles home Saturday night, and almost got busted by her security guards!

When a patrol saw Gosling's classic car parked outside of Mendes' place, they investigated. Eva had to come out to assure the guard that she was OK!

Eva tells the guard the car belongs to "a friend." Her security was right to be on high alert -- Eva has had issues with stalkers this year, and last week stopped at a police station after she became fearful that a car was following her around Hollywood.

But, looks like the only crime here is one of passion! Watch Eva talk the guards down in our exclusive video above!