After 10 months out injured, Danny Welbeck took barely 10 minutes on his return from surgery to score a precious goal for Arsenal.
The striker's header in the fifth minute of stoppage time secured a 2-1 victory over 10-man Leicester on Sunday, cutting the surprise Premier League frontrunner's lead over the London club to two points.
"It has been a bit of a rollercoaster for me, missing a lot of football ... it was difficult," Welbeck said. "To get that winning goal is a beautiful feeling."
Leicester was leading through Jamie Vardy's 45th-minute penalty at the Emirates Stadium when Danny Simpson received two yellow cards in the opening nine minutes of the second half.
Arsenal had failed to register a shot on target at that stage, but Arsene Wenger's substitutions delivered as intended as the hosts exploited their man advantage.
Theo Walcott equalized with 20 minutes to go and Welbeck, who replaced Alex Oxlade-Chamberlain in the 83rd minute, headed in Mesut Ozil's free kick on his return from left knee surgery.
"In the last two training sessions he was very strong," Wenger said. "Everyone is extremely happy for [Welbeck] because he has been out for 10 months which is an eternity for a player."
Arsenal on Leicester's heels
It ensured Arsenal became the first team to complete the double this season over Leicester, which has only lost three times in the league to gatecrash the elite after narrowly surviving relegation last year.
This loss punctures the cautious optimism building at Leicester that it could win the top prize in English football for the first time in its 132-year history.
But Leicester has still collected six points from a possible nine in the last two weeks, having beaten Liverpool and Manchester City.
And while top-four rivals Arsenal, Tottenham and City have European and FA Cup games over the next seven days, Leicester has two clear weeks until the league resumes.
Ranieri is giving his players a week off from the club to escape the freezing conditions and mounting expectation at home.
"I said to [the players], `Don't worry. It's OK. You are top of the league with two points more,"' Ranieri said. "They go, I don't know where. Dubai? Wherever they want."
Ranieri's team had been fortunate to survive the opening 15 minutes unscathed in north London after the hosts made a dangerous start with two attempts in the opening two minutes, including Alexis Sanchez heading wide.
While Vardy and Riyad Mahrez have won plaudits for their lethal attacking contribution, goalkeeper Kasper Schmeichel has been integral to Leicester's title charge.
Schmeichel could, however, have looked reckless when he raced out his penalty area to halt Aaron Ramsey's advance. But the daring move succeeded and, in a rapid response, Marc Albrighton crossed to Vardy whose first effort of the game was a header saved by Petr Cech.
This unexpected title challenge has been forged on making the most of counterattacks, with Leicester having the third-worst possession statistics in the league.
N'Golo Kante was also wreaking havoc, unsettling Arsenal's defense. His curling shot five minutes before halftime was only kept out of the net by Cech's one-handed save.
The opener came just before half time with Kante down on the field. Play was allowed to continue, with Vardy cutting in from the right toward goal before Monreal stuck a boot out to block him. Vardy sent Cech wrong way from the spot to make it 19 goals in 26 games for the league's top scorer.
"We are staying up," Leicester fans responded ironically. The target for the season was survival. Never has a Premier League team exceeded expectations so spectacularly but Leicester's title dreams took a knock after the break.
Simpson was booked for bringing down Sanchez in the 49th and shown a second yellow card five minutes later for hauling down Giroud.
Ranieri's response was to sacrifice Mahrez, who was replaced by defender Marcin Wasilewski.
"It was a mental test for us," Wenger said. "We took all the risks to win it."