Jack Porter became Arsenal's youngest-ever player to start a first-team game when the 16-year-old goalkeeper made his debut against Bolton in the Carabao Cup on Wednesday.
At 16 years, 72 days old, Porter surpasses club icon Cesc Fabregas, who was 16 years, 177 days when he started against Rotherham in October 2003.
Porter was selected in place of first choice David Raya, who was ruled out with a thigh injury, Arsenal said. Raya left Etihad Stadium with a bandage around his right knee after picking up an injury in last weekend's 2-2 draw at Manchester City.
With Neto -- a summer loan signing from Bournemouth -- cup-tied and 18-year-old understudy Tommy Setford also injured, Arsenal boss Mikel Arteta has called on Porter, who only turned 16 in July.
Porter has trained with the first team on a few occasions previously and was named among the substitutes for last week's Champions League trip to Atalanta which ended 0-0.
He only signed scholarship terms with the Gunners in the summer and cannot agree a professional contract until next year when he turns 17.
As ESPN reported on deadline day, Arsenal attempted to sign two goalkeepers late in the window, having allowed Aaron Ramsdale to join Southampton in a permanent deal and Karl Hein to move to Real Valladolid on loan.
After securing Neto's arrival, they explored a deal for Joan García at Espanyol while also making an approach for Wolves' Dan Bentley but were unable to secure an agreement.
Arteta rotated his side for the game against Bolton with youngsters Ethan Nwaneri and Miles Lewis-Skelly among those included, while Raheem Sterling made his first start after arriving on a season-long loan from Chelsea.
Nwaneri holds the record as the youngest player to represent Arsenal's first team after coming on as a substitute aged 15 years, 181 days in September 2022.
Information from The Associated Press contributed to this report.