Keane Lewis-Potter was on target as Brentford beat Colchester United 1-0 to set up a Carabao Cup third-round tie with Leyton Orient.
Lewis-Potter netted just before the break, turning home from close range having been found in the box by Kevin Schade, while Hákon Valdimarsson saved Jack Payne’s 81st-minute penalty after Frank Onyeka brought down Mandela Egbo in the box.
Thomas Frank made nine changes to the side that lost to Liverpool on Sunday.
Fábio Carvalho and Sepp van den Berg, both signed from Liverpool this month, were in from the start at JobServe Community Stadium, as was defender Ben Mee for the first time since February.
Ryan Trevitt, who made his professional debut against Colchester two years ago, was selected at right-back.
The first chance fell to the hosts. Aaron Donnelly launched a long throw into the box, which set the tone for the U’s’ direct approach during the opening stages, and Valdimarsson went down after a robust challenge from Ben Goodliffe.
Tom Hopper reacted fastest in a crowded area, seizing on the loose ball and driving hard and low towards goal, but his effort was straight at the grounded Bees keeper.
At the other end, Schade darted to the near post and headed Carvalho’s corner narrowly wide.
Midway through the half, Trevitt brought down a clever lofted pass from Mikkel Damsgaard and cut the ball back for Carvalho inside the six-yard box. Goodliffe made a last-ditch intervention and Onyeka’s strike on the follow up was blocked.
On 34 minutes, a short corner routine involving Carvalho and Trevitt led to the latter whipping a cross into the box. It was Lewis-Potter who made contact, but his glancing header dropped wide of the far post.
The Bees ended the half on top, dominating possession and patiently probing for an opener.
Carvalho exchanged passes with Lewis-Potter on the edge of the area and his low drive from 20 yards was comfortably held by Matt Macey.
Frank’s side took the lead in the final minute of the opening 45. Trevitt played a long ball up the channel and U’s defender Donnelly, having position himself between Schade and the goal, went down softly.
The referee rightly allowed play to continue, leaving the German to square for Lewis-Potter who faked a shot to floor Rob Hunt before walking the ball into an empty net.
Carvalho’s tame effort was gathered by Macey in the final action of the half.
Shortly after the restart, following a quick breakaway involving Lewis-Potter and Carvalho, Schade teed up Trevitt on the edge of the box and the B-team graduate’s first-time strike flew over the bar.
A clever free-kick caught Colchester out but Macey spread himself to deny Schade from close range.
Substitute Jack Payne’s speculative effort was then held by Valdimarsson.
On 81 minutes, Mandela Egbo drew a foul from Onyeka inside the penalty area and the referee pointed to the spot. Jack Payne opted to shoot down the middle and Valdimarsson superbly saved with his trailing leg.
Lewis-Potter’s devilish cross narrowly evaded a stooping Yoane Wissa as the Bees looked to heed their warning and put the game to bed.
After a slick move down the right, Macey advanced off his line quickly to narrow the angle and deny Myles Peart-Harris in the fourth of seven additional minutes.
Nathan Collins then headed inches wide of Macey’s right post, connecting with Mathias Jensen’s in-swinging free-kick.
The Bees' reward for their victory in Essex is a third-round tie against Leyton Orient at Gtech Community Stadium.
Colchester United: Macey; Hunt (Egbo HT), Goodliffe, Iandolo (Gordon HT); Woodyard (Payne HT); Anderson (Edwards 62), Donnelly, Read, Oni (Tovide 66); Hopper, Ihionvien
Subs not used: Smith, Bendle, Thorn, Terry
Brentford: Valdimarsson; Trevitt, van den Berg, Mee, Janelt (Collins 73); Onyeka (Konak 89), Yarmoliuk; Damsgaard (Jensen 73), Carvalho (Peart-Harris 84), Lewis-Potter; Schade (Wissa 73)
Subs not used: Cox, Roerslev, Ji-soo, Morgan