Arsene Wenger urged his misfiring Arsenal squad to stick together after Watford claimed a 2-1 FA Cup quarter-final victory over the holders.
Danny Welbeck - who did not start in attack because it "was not possible medically", according to Wenger - climbed off the bench to pull a goal back in the 88th minute to prompt a frantic finish.
Ultimately, goals from Odion Ighalo and Adlene Guedioura saw Watford through to a Wembley semi-final and ended Wenger's hopes of winning a third straight FA Cup.
The likelihood is now a trophyless season for Arsenal, with Wenger's management coming under increasing scrutiny from the Emirates Stadium faithful.
A 2-0 first-leg deficit is likely to result in a last-16 Champions League exit at the hands of holders Barcelona when they travel to Camp Nou on Wednesday, by which point Arsenal could be 11 points behind Premier League leaders Leicester City.
"Of course you cannot guarantee that you win the cup. We were in the quarter-final and we gave everything to win," Wenger told BT Sport as he strained for reasons to be optimistic.
"Let's focus on the next game and I believe it is important we stick all together and give our best in Barcelona.
"Of course [the players will need picking up]."
Wenger sympathised with his defeated players after they were punished for missed chances by an impressive and clinical Watford performance.
"It is very difficult to understand how we lost the game but we had to take two chances and we didn't," he said.
"At the end of the day, you have to be realistic in this job and we have lost a game we shouldn't have lost.
"I believe we put quite a decent performance in and in the end we lost the game. It's the cup and that's what it is about."
Wenger added: "We missed something in the final ball in taking our chances. In the second half I felt we didn't come back with the same sharpness and focus in the first 10 or 15 minutes and that was punished.
"We lost a header on the throw-in [for Ighalo's goal] and after that all went for them. They had, perhaps, that special focus. For us it is frustrating."