After suffering defeat in Junín a tight second leg was expected in Tucumán on Sunday but San Martín put five past beleaguered Sarmiento to seal a return to the Primera after nine years away and set up a first top flight Clásico Tucumano in 37 years.
Rubén Forestello’s side were rampant from kick off in front of their vociferous home support and had turned around the first leg deficit inside three minutes.
The impressive Lucas Acevedo volleyed in unmarked from a corner with 90 seconds on the clock and a minute later Gonzalo Rodríguez broke away to double the lead.
A stunned Sarmiento hadn’t yet started and their slender lead had already been reversed.
The Verde responded and Nicolás Miracco hit the woodwork as the first half went back and forth but unable to pull back level, San Martín took a grip on the tie minutes after the restart.
The second half was barely two minutes old and once again the home side flew out of the traps with Claudio Bieler sweeping in another swift counter.
Sarmiento came close to pulling a goal back but when Acevedo headed a fourth after 65 minutes the outcome looked certain. By the time a well worked free-kick saw Bieler bend in his second and San Martín’s fifth, the celebrations were in full swing and smoke filled the Estadio La Ciudadela.
With limited visibility, Nahuel Estévez fired a long-range consolation past the excellent Ignacio Arce in goal but San Martín were heading back to the top flight.
El Ciruja accompany Aldosivi up from the B Nacional ahead of next season’s 26-team Superliga and already supporters in Tucumán will be preparing for the clásico.