After a rare English Premier League swap deal, Alexis Sanchez and Henrikh Mkhitaryan made an immediate impact at their new homes on Saturday.
Sanchez injected a fresh dose of dynamism to Manchester United and scored — immediately after a penalty was parried — on his debut to seal a 2-0 victory over Huddersfield.
"I don't think it is a dream goal for Alexis," United manager Jose Mourinho said. "Every player prefers to score a penalty. But it also shows his attention to detail, his reaction and his desire."
Mkhitaryan, who struggled to convince Mourinho of his qualities at United, marked his first Arsenal start by providing three assists — including one for fellow new recruit Pierre-Emerick Aubameyang — in a 5-1 rout of Everton.
"The two players integrated well into our game and they looked as if they had played for us forever," Arsenal manager Arsene Wenger said.
When so much focus was on Mkhitaryan and $80 million record signing Aubameyang, Aaron Ramsey chose the wrong day to score his first ever hat trick.
"He didn't do it until now because I think he rushed, sometimes, with his finishing," Wenger said. "He looks much calmer."
For Arsenal and United, the January signings were made with an eye on next season in the Premier League. Any title aspirations faded long ago.
Even though Manchester City dropped points for only the fourth time this season in a 1-1 draw at Burnley, the leader's advantage was still only cut to 13 points by United with 12 games remaining.
The tussle to stay in the Premier League is far tighter.
Southampton escaped the relegation zone after winning at last-place West Bromwich Albion 3-2 to end a 12-match winless run in the league.
Swansea is out of the danger zone only on goal difference after drawing with Leicester 1-1.
But Stoke sunk back into the bottom three after Bournemouth followed up recent fine wins against Arsenal and Chelsea by beating the less illustrious opposition 2-1.
Brighton ended West Ham's six-match unbeaten run by winning 3-1 to move three points clear of the drop zone.
SANCHEZ SAVES UNITED
Responding to Wednesday's loss at Tottenham with a victory should have mellowed Mourinho. Especially with his latest striking addition, Sanchez, and summer signing Romelu Lukaku scoring against Huddersfield.
Instead the United manager turned on his own fans at Old Trafford.
"The atmosphere is a bit quiet," he grumbled after avenging a loss to Huddersfield earlier in the season.
Mourinho might have incensed his own fans and the club's most expensive player, Paul Pogba. The 105 million Euro midfielder was dropped from the starting lineup.
"The intention was not to punish anyone," Mourinho said. "Paul is a fantastic player — no doubt for me one of the most talented midfield players in the world."
RAMSEY SHREDS EVERTON
Everton manager Sam Allardyce called the capitulation at Arsenal "pathetic." It was an uncomfortable return to Emirates Stadium for Theo Walcott.
Ramsey diverted Mkhitaryan's cross in the net after just six minutes and, after Laurent Koscielny headed Arsenal further in front eight minutes later, the Wales midfielder was on target again in the 19th with a deflected strike.
Arsenal was running Everton ragged, and Aubameyang ran onto Mkhitaryan's pass and dinked the ball over goalkeeper Jordan Pickford in the 37th.
Dominic Calvert-Lewin headed in a consolation in the second half, but Ramsey completed his treble in the 74th from another of Mkhitaryan's pinpoint crosses.
Pep Guardiola didn't even bother to fill his quota of substitutes at Burnley, taking only six players for the City bench due to injuries.
"I could have called one of the second team," the City manager said, "but we decided they were not going to play."
After being invincible in the first half of the season, City's shine has faded in recent weeks. Only two points have been collected from the last three away games that saw Liverpool end City's unbeaten start.
City was looking on course for a win courtesy of Danilo's 22nd-minute strike but paid the price for a glaring miss by Raheem Sterling when Johann Berg Gudmundsson leveled for Burnley in the 82nd.