Match ends, Swansea City 0, Arsenal 4.
Arsenal returned to the top four with a handsome victory at Swansea City, consigning Paul Clement to a demoralising defeat in his first Premier League game in charge of the hosts.
Having initially been frustrated by their opponents, the Gunners led at half-time thanks to Olivier Giroud's powerful, close-range finish.
Alex Iwobi's strike looped in via a big deflection off Jack Cork to double their advantage, and Kyle Naughton scored a second Swansea own goal when he turned another Iwobi shot into his own net.
Alexis Sanchez completed the rout to lift Arsenal up to third in the table, while Hull's win over Bournemouth means Swansea return to the bottom of the table.
Despite some encouraging signs early in the game, this was a stark reminder to former Bayern Munich assistant manager Clement of the enormous task he faces to steer the Swans to safety.
By contrast, the ruthless nature of Arsenal's display - particularly in an extremely one-sided second half - will surely give Arsene Wenger renewed hope of mounting a serious title challenge.
- Wenger tips Swansea to stay up
- Relive Arsenal's thrashing of Swansea
- Reaction from all of Saturday's Premier League matches
Arsenal ease their away-day blues
The Gunners' bid for a first title since 2004 had stuttered lately, largely due to an away record of one point from their past three Premier League matches on the road.
Although they started slowly against the high-pressing Swans, the visitors settled thanks to a goal from an increasingly reliable source.
Giroud started this game with 12 goals from his past 17 shots on target, and the France striker was clinical with his first effort on this occasion, seizing on Mesut Ozil's blocked header and firing the ball into the roof of the net from six yards.
Arsenal took control from that point and a period of concerted pressure early in the second half saw the floodgates open.
There was an element of luck about the second and third goals, but they were no more than the Gunners deserved for their dominance of possession and inventive use of it around the Swansea penalty area.
The irrepressible Sanchez finally got in on the act after 73 minutes, volleying in from close range to score his 21st goal in 32 Premier League appearances.
Clement's tall order
There was a certain symmetry to Clement's first league game in charge, coming as it did against an Arsenal side who had beaten Swansea 3-2 at the start of his predecessor Bob Bradley's short tenure.
One of Clement's priorities is to improve the Swans' defence - the most porous in the top flight - and the way his players shackled Arsenal early on with their high pressing was encouraging.
But after falling behind, the home side simply collapsed.
They were slack in their marking and slow to react to the Gunners' movement, summed up by the space in which Sanchez found himself in the Swansea box when he scored the fourth.
Swansea find themselves back at the bottom of the table and with a tough run of fixtures to come - Liverpool and Manchester City are two of their next three opponents.
The threat of relegation is as startling a reality as ever.
Man of the match - Alexis Sanchez (Arsenal)
'They had problems containing us'
Swansea boss Paul Clement: "It is very disappointing. The first half we were in the game and looked solid defensively, even though we did not do enough offensively. We got caught on the counter for the first goal.
"We had a big claim for a penalty. Looking back on it, it is a penalty. In the second half, we started poorly and then it was an uphill struggle after the first own goal. Arsenal showed how much quality they have offensively."
Arsenal manager Arsene Wenger: "The first half was very intense physically, they gave a lot in the first half and then our pace took over. They had problems containing us.
"In the second half, you could see we could create chances. Our transition and accuracy of passing was very good. We were fortunate with the goals, but the chances were there."
Match of the Day analysis
Ex-England midfielder Danny Murphy: "Arsenal have missed Mesut Ozil for a few games but he made a big difference against Swansea. Ozil was exceptional in crucial areas of the pitch.
"He makes the right decisions nine times out of 10. Ozil gives that extra quality and class in final third. Arsenal are a better team when he is in it. Alexis Sanchez and Ozil together make Arsenal an exceptional and dangerous team.
"Paul Clement will be on training pitch as long as he can. He is a workaholic. He will be quite savvy in the transfer market. He will improve Swansea but whether it will be enough, we'll have to wait and see."
Ex-Arsenal striker Ian Wright on Swansea's penalty appeal: "Swans boss Paul Clement said he thought it was a penalty. I didn't think it was. Ki Sung-yueng was searching for the (Laurent Koscielny's) foot and I think he kicks the foot. Those have been given."
On Sanchez's reaction to being taken off: "He is disappointed. He doesn't want to be taken off. He's so integral to Arsenal. If Sanchez is not there, there is massive problem."
It does not get any easier for Swansea as they travel to Liverpool next Saturday (kick-off 12:30 GMT), while Arsenal host Burnley on Sunday, 22 January (kick-off 14:15).
Sanchez central to Arsenal - stats of the day
- Arsenal have scored 27 goals away from home in the Premier League this season, at least five more than any other side.
- The Gunners have scored four or more goals in four away Premier League games this season, their most in a single campaign since 2002-03.
- Giroud has scored in each of his past nine starts, netting 11 goals in total.
- Sanchez has been involved in more goals (21) than any other Premier League player this season (14 goals, seven assists).
- Swansea became the first team to score two own goals in a Premier League match since QPR against Liverpool in October 2014.
- The Swans have conceded four or more goals in three of their past five Premier League home games, having only let in four or more in three of their previous 62 league games at the Liberty Stadium.
- 4Ki Sung-yuengBooked at 43mins
- 24CorkSubstituted forMcBurnieat 71'minutes
- 12DyerSubstituted forFerat 55'minutesBooked at 78mins
- 23G Sigurdsson
- 9LlorenteSubstituted forBastónat 70'minutes
- 5van der Hoorn
- 11ÖzilSubstituted forPérezat 79'minutes
- 7SánchezSubstituted forWelbeckat 79'minutes
- 12GiroudSubstituted forOxlade-Chamberlainat 60'minutes
- Mike Jones
- Shots on Target
Second Half ends, Swansea City 0, Arsenal 4.
Attempt missed. Borja Bastón (Swansea City) header from the centre of the box is just a bit too high. Assisted by Oliver McBurnie with a cross.
Foul by Shkodran Mustafi (Arsenal).
Borja Bastón (Swansea City) wins a free kick on the left wing.
Delay over. They are ready to continue.
Delay in match Laurent Koscielny (Arsenal) because of an injury.
Attempt blocked. Wayne Routledge (Swansea City) right footed shot from the left side of the box is blocked. Assisted by Oliver McBurnie.
Attempt saved. Granit Xhaka (Arsenal) left footed shot from outside the box is saved in the bottom right corner. Assisted by Aaron Ramsey.
Attempt blocked. Alex Iwobi (Arsenal) right footed shot from the centre of the box is blocked. Assisted by Alex Oxlade-Chamberlain.
Attempt saved. Gylfi Sigurdsson (Swansea City) left footed shot from outside the box is saved in the bottom right corner. Assisted by Borja Bastón.
Offside, Swansea City. Oliver McBurnie tries a through ball, but Borja Bastón is caught offside.
Attempt saved. Granit Xhaka (Arsenal) left footed shot from outside the box is saved in the bottom right corner.
Foul by Gabriel (Arsenal).
Wayne Routledge (Swansea City) wins a free kick in the defensive half.
Substitution, Arsenal. Danny Welbeck replaces Alexis Sánchez.
Substitution, Arsenal. Lucas Pérez replaces Mesut Özil.
Leroy Fer (Swansea City) is shown the yellow card for a bad foul.
Aaron Ramsey (Arsenal) wins a free kick on the left wing.
Foul by Leroy Fer (Swansea City).