The 22-year-old came in for the injured Martin Odegaard at the Brentford Community Stadium, and his long-range effort early in the second half capped off an utterly dominant display from Mikel Arteta’s side.
Browsing: Brentford Community Stadium
Dennis, 24, enjoyed a stellar season with the Hornets in the Premier League despite the club being immediately relegated back to the Championship.
Thomas Frank’s side ran out 4-1 winners over Chelsea in their most recent clash, while the Hammers head into the game having just drawn 1-1 with Lyon in the first leg of their Europa League quarter-final.
Six points currently separate the two teams in the Premier League standings, though the Clarets in 18th have two games in hand on the Bees in 15th place.
The Magpies have moved out of the relegation zone into 17th position due to their impressive run of results in recent weeks, while Brentford sit 14th, just four points above the bottom three.
The Bees went down 2-0 to Manchester City in midweek, while Patrick Vieira’s side were held to a 1-1 draw by a resurgent Norwich City.
The Bees suffered a 3-1 defeat to Manchester United in midweek, while Bruno Lage’s side came up trumps by the same scoreline against Southampton last weekend.
The newly-promoted Bees currently sit one point above their next opponents, who are seemingly back on track after their dramatic win over Manchester United last weekend.
Thomas Tuchel’s side eased past Southampton before the international break, while the Bees got the better of West Ham United 2-1.
Both sides enter the contest having marched to convincing wins in their respective EFL Cup showdowns, with Thomas Frank’s side putting seven past Oldham Athletic while the Reds eased to a 3-0 win over Norwich City.