Victor's second-half header was enough to send Real Mallorca level at the top of the Primera Division table for at least 24 hours.
Mallorca had to wait until the 75th minute until they broke down a stubborn Real Sociedad rearguard when Victor stooped to head in Javi Marquez's cross.
The Islanders almost immediately relinquished their hard-fought lead, however, with debutant Anderson Conceicao blocking Xabi Prieto's goalbound shot off the line moments later.
Mallorca's win maintained their unbeaten start and moved them level with Malaga at the top of the table although they could be passed by a trio of clubs, headed by Barcelona, tomorrow.
Sociedad almost stole into an early lead when Imanol Agirretxe snuck in behind the defence to meet a free-kick but he could only turn the ball over with an out-stretched leg.
Mallorca controlled possession for the remainder of the half without causing Claudio Bravo too many headaches in the away goal.
Michael Pereira fired wastefully over from a Tomer Hemed cross while Tomas Pina headed a Marquez free-kick into Bravo's arms.
Brazilian defender Anderson then wasted his new side's best chance of the half when unmarked he headed a corner straight at Bravo.
The home side continued to control possession after the break but while Bravo was busy he remained comfortable.
The Chilean easily collected a low drive from Victor before also easily dealing with a Marquez free-kick.
Mallorca were, however, starting to step up the pressure and the breakthrough came with 15 minutes to go.
Marquez, whose delivery had caused problems all night, lofted in a perfectly-weighted cross and Victor got across his marker before heading home from six yards.
Sociedad were almost immediately back on level terms when home goalkeeper Dudu Aouate palmed a cross straight to Prieto but his close-range effort was blocked by Anderson.
Substitute Antoine Griezmann then fired a free-kick just over as Mallorca collected the win.