San Lorenzo, another of Argentina's so-called Big Five teams, had their hopes of a winning start to the Clausura championship to edge away from relegation danger shattered in a 4-1 defeat at Lanus.
Olimpo attacked from kick-off and goalkeeper Agustin Orion had to go down sharply at his left-hand post to push away a shot from Martin Rolle and prevent Boca from going behind inside half-a-minute.
Urged on by a packed Bombonera bedecked in their blue and yellow colours, Boca found their feet after the opening 10-minute onslaught during which they were mostly forced into their own half and captain Juan Roman Riquelme came in for close attention from Olimpo's defenders.
"It's important to start with a win. We'd gone three or four tournaments without being able to start with a win," Riquelme told broadcaster TV Publica. Boca were held 0-0 at Olimpo in their opening match of the Apertura in August.
Bueno scored just before the hour on Friday but by then the Saints were four goals down, having conceded three in the opening half hour. Former River Plate striker Mariano Pavone scored twice, including Lanus's fourth early in the second half.
"We had our revenge," Pavone told reporters.
San Lorenzo's frustration boiled over in the final quarter-of-an-hour when two defenders, Nicolas Bianchi Arce and Fernando Meza, were sent off.
