Raheem Sterling netted his first goal for Arsenal, and Jack Porter made history as the club's youngest-ever starter in a commanding 5-1 victory over Bolton in the League Cup on Wednesday.
Meanwhile, Liverpool advanced to the last 16 with a similar 5-1 triumph against struggling West Ham.
Sterling, making his maiden start for Arsenal following his transfer from Chelsea on deadline day, scored in the second half of the third-round clash at the Emirates Stadium.
The 29-year-old hopes this goal signals the beginning of a career revival after a challenging two-year stint at Chelsea.
Gunners boss Mikel Arteta made seven changes from Sunday's stormy 2-2 draw at Premier League champions Manchester City, including giving goalkeeper Porter his record-breaking debut in place of the injured David Raya.
At 16 years and 72 days old, Porter became the youngest player ever to start for Arsenal, surpassing the previous record holder, Cesc Fabregas, who was 16 years and 177 days when he played against Rotherham in 2003.
Porter is Arsenal's second-youngest player overall, after Ethan Nwaneri, who was 15 years and 181 days when he made his debut in 2022.
Declan Rice put Arsenal ahead in north London after 16 minutes with a clinical finish from the edge of the area for his first goal of the season.
Fittingly on Porter's record-setting day, it was Nwaneri who doubled Arsenal's lead in the 37th minute with his first goal for the club. The 17-year-old forward celebrated his first Arsenal start with a close-range finish from Sterling's cross.
Nwaneri struck again four minutes after halftime with a composed strike from 12 yards.
Porter had to pick the ball out of the net for the first time in his Arsenal career in the 53rd minute when Aaron Collins jinked around him and slotted into the empty net.
Sterling netted in the 64th minute, tapping in after Bukayo Saka's cross was spilled by Bolton keeper Luke Southwood, and Kai Havertz grabbed the fifth from close range in the 78th minute.
At Anfield, Diogo Jota and Cody Gakpo scored twice as Liverpool's understudies demolished West Ham, increasing the scrutiny on Julen Lopetegui.
Under pressure after winning only one of his first five league games since replacing David Moyes, former Real Madrid chief Lopetegui made eight changes from the 3-0 defeat against Chelsea last weekend.
Despite spending 120 million pounds ($159 million) on new signings, Lopetegui was jeered by furious fans on Saturday after becoming the first West Ham manager to suffer three consecutive home losses to start a season.
The Hammers took a surprise lead in the 21st minute as Kostas Tsimikas's miscued clearance deflected in off Liverpool defender Jarell Quansah for a farcical own goal.
Reds manager Arne Slot made nine changes from Saturday's win over Bournemouth as Italy forward Federico Chiesa made his first start since his move from Juventus.
Jota equalized four minutes later, out-jumping West Ham keeper Lukasz Fabianski to nod in Chiesa's volley.
Jota struck again in the 49th minute as he exchanged passes with Curtis Jones and drilled past Fabianski.
Mohamed Salah came off the bench to score in the 74th minute with a simple finish after Alexis Mac Allister's shot was pushed into his path.
West Ham were in disarray, and Edson Alvarez was sent off in the 76th minute for a second booking after chopping down Salah.
Capping another torrid day for Lopetegui, Gakpo smashed home from 18 yards in the 90th minute and then guided a deflected effort beyond Fabianski moments later.
