**Flávio Bolsonaro leads trader pricing at 57.3% to Lula’s 43.5% heading into the October 4 first round because recent polling momentum has narrowed or erased Lula’s earlier edge in a polarized contest.** Multiple September surveys from Datafolha, Quaest, and AtlasIntel show the two statistically tied or within the margin of error in both rounds, with Flávio consolidating right-wing support as the PL nominee and son of the ineligible Jair Bolsonaro. Late-campaign factors include a right-wing surge tied to Supreme Court controversies, voter fatigue with the incumbent, and Flávio’s emphasis on security and tax issues. Fragmented alternatives such as Augusto Cury, Ronaldo Caiado, and Renan Santos remain in single digits and show little path to the runoff, reinforcing the binary dynamic reflected in market pricing.