Resurgent Arsenal continued to resurrect their Premier League season after thumping West Bromwich Albion 4-0 to pile more misery on the Baggies.
Alexandre Lacazette's second-half brace added to excellent strikes from Kieran Tierney and Bukayo Saka.
Earlier, north London rivals Tottenham kept the pressure on Liverpool and Manchester United at the top with a 3-0 home win against Leeds.
At The Hawthorns, Arsenal overwhelmed West Brom to record three successive league victories for just the second time under Mikel Arteta.
The Gunners only climbed to 11th but they are at least within striking distance of the top six, sitting three points behind Chelsea having played a game more.
WBA remain second bottom, with just one win, and have now conceded 12 goals in Sam Allardyce's three home games.
No team with eight points or fewer from their opening 17 matches have avoided relegation from the Premier League.
Arsenal grabbed the lead after 23 minutes when left-back Tierney twice beat defender Darnell Furlong on the left and cut inside before firing high with his right foot past Johnstone from 15 yards.
Five minutes later it was 2-0 when Emile Smith Rowe swapped passes with Saka and Lacazette before Saka, who had continued his run unmarked, tapped in.
Arsenal wrapped up the points with two more quickfire goals from Lacazette.
Saka's 61st-minute cross was turned onto his own post by Semi Ajayi, who then blocked Smith Rowe's follow-up strike, but Lacazette gobbled up the rebound.
The second, after 64 minutes, was equally as simple as the French striker converted Tierney's cross from close range.
"It was a convincing win, and to win three games over the festive period in the Premier League is not easy," Arsenal manager Mikel Arteta told BT Sport.
"The first goal with Kieran was terrific and the second goal with the combination between players was fantastic as well.
"The clean sheet, our second in a row, gives us a platform to go on and win the games and we looked more creative in the final third.
In London, Tottenham skipper Harry Kane scored from the spot on 29 minutes after Ezgjan Alioski had fouled Steven Bergwijn and the England captain then provided the cross as Son Heung-min added the second before halftime.
Toby Alderweireld made it 3-0 and though Spurs defender Matt Doherty was sent off late on for his second yellow card, his side moved just four points behind leaders Liverpool, who play at Southampton on Monday. Leeds remain 11th.
Elsewhere, Sheffield United's problems deepened as the bottom side lost 2-0 at Crystal Palace.
Jeffrey Schlupp and Eberechi Eze scored the first-half goals that gave the Eagles victory and saw them climb to 12th.
Brighton, still minus Australian goalkeeper Mat Ryan in their squad, came from 3-1 down to clinch a 3-3 draw at home to Wolves and put themselves three points above the bottom three.