Odion Ighalo scored twice as a buoyant Watford won 3-0 at home to Liverpool on Sunday to consolidate seventh position in the Premier League, only one point behind the top four.
It was a bad blow for Juergen Klopp's side, who would have overtaken them with a win but remained ninth, having taken only one point from three games.
Nathan Ake, the Dutch Under-21 international on loan from Chelsea, scored in only the third minute after a howler from Hungarian goalkeeper Adam Bogdan, who was deputising for the injured Simon Mignolet.
Bogdan was soon beaten again on an unhappy league debut when Watford captain Troy Deeney sent leading scorer Ighalo away to net for the fourth game in succession. The Nigerian made it 12 for the season five minutes from time.
It was the first time since April 1987 that Watford, promoted to the top flight again this season, have won four successive games at this level of English football.
"It was an amazing victory against an amazing team," Quique Sanchez Flores, Watford's manager, told the BBC.
Yet the Spaniard was keen not to get too carried away with his side's progress. "We should be humble, we have a lot of matches to play," he added.
"Four wins back-to-back is massive and starts our so-called tough run that everyone's talking about," a jubilant Deeney added on Sky Sports.
"We're just doing our stuff and people have got to be worried to come here now.
Deeney and Ighalo have now scored 17 of the team's 21 goals between them this season. The captain, who plays just behind his team-mate, offered an insight into their understanding when describing the first goal.
"I was fighting for the ball but I know he's going to make a run. He makes it easy for me because he's so quick and strong."
"I know when he gets the ball, he will play it behind the defence," added Ighalo, which was just what happened.
The predictability of the move did not please Klopp, who criticised his team's "bad reaction" to conceding twice in the opening quarter of an hour.
He insisted the first goal should not have been allowed, however, claiming that Bogdan had both hands on the ball after initially dropping it from Ben Watson's corner.
"I think it's a foul, it was a wrong decision, but our reaction was really bad," he said.
"We lost our mind and lost a very easy second goal, when we can defend better.
Ake's goal, stabbed over the line from barely a metre, was the left-back's first in English football, confirming the good impression he has made at Watford.
Watford's second did not reflect well on Martin Skrtel, who seemed to have forced Ighalo wide from Deeney's pass but allowed him shoot from a wide angle.
Skrtel limped off before half-time and Divock Origi came on hoping to make an impression as dramatic as last weekend's when his goal in the sixth minute of added time earned Liverpool a draw against West Bromwich Albion.