Sean Dyche praised his stretched squad following a bittersweet penalty shoot-out victory over Sheffield United.
The Clarets deserved a third round tie at Millwall after coming from behind to defeat the Blades 5-4 on penalties at Turf Moor.
But the loss of Johann Berg Gudmundsson to a twisted knee, following a heavy challenge from Jack Robinson early in the game, left Dyche rueing the loss of another key player in a squad already stretched to the limit ahead of the start of the Premier League season.
The Clarets boss said: “It was a tight game.