SAO PAULO, Sept 2 (Reuters) - Brazilian President Luiz Inacio Lula da Silva's lead over right-wing challenger Senator ‌Flavio Bolsonaro narrowed further ahead of October's election, a ‌Quaest poll commissioned by Globo showed on Wednesday.

• In a simulated second-round ​runoff, Lula would win 42% of the vote, compared with 41% for the eldest son of former President Jair Bolsonaro.

• Quaest called this a technical tie, as its poll has a ‌margin of error of ⁠2 percentage points.

• An earlier Quaest poll released on August 14 had Lula leading Bolsonaro by 43% ⁠to 40%.

• In a first-round scenario, Lula would lead with 37% of the votes, followed by Bolsonaro (30%), Augusto Cury (10%) and Renan ​Santos (3%).

• Quaest ​is the third major survey ​this week to show ‌author and psychiatrist Cury in third place, as TV appearances and strong social media reach have lifted his standing in polls.

• If no candidate wins more than 50% of valid votes in the first round, the two frontrunners advance to a ‌runoff.

• Quaest surveyed 2,004 people ​between August 30 and September 1.

• ​This is the first ​Quaest poll released since the start of the ‌television and radio political campaign.

• It ​also comes after ​new developments in an investigation involving Lula's son, Fabio Luis Lula da Silva, over allegations he improperly assisted ​a lobbyist in ‌dealings with the Health Ministry. Lula's son has denied ​the allegations.

(Reporting by Gabriel Araujo; Writing by Isabel ​Teles; Editing by Alexandra Hudson)