ATP National Bank Open tennis tips: Preview and best bets for round four

Andy Schooler previews the fourth-round matches at the ATP National Bank Open in Montreal, dated August 8, 2026, following a 9/5 winner in his previous column. His headline bet is Thiago Agustin Tirante to beat Learner Tien at 5/2 with Sky Bet, bet365, and betway. The preview also covers the match between Ben Shelton — last year's champion in Toronto — and 19-year-old Brazilian Fonseca, who is ranked just seven places below Shelton.