GOODISON PARK, England -- If this is the beginning of Manchester United turning a corner, Erik ten Hag can thank two teenagers for grabbing the steering wheel.

Playing an in-form Everton at Goodison Park, which at times felt like a bear pit given the home fans' anger at the Premier League for their 10-point deduction, 19-year-old Alejandro Garnacho scored a wonder goal and, with chaos at times exploding all around him, 18-year-old Kobbie Mainoo was the calmest man on the pitch on his full Premier League debut.

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This week -- with three away games against Everton, Galatasaray and Newcastle in the space of six days -- could prove pivotal in United's season and thanks to Garnacho and Mainoo, they are off to the perfect start.

Marcus Rashford's second goal of the season from the penalty spot and Anthony Martial's first league goal since April earned a 3-0 win and meant that Ten Hag, who spent the afternoon in the stands because of a touchline suspension, was able to talk glowingly about his team's biggest league win of the season.

"It was a good performance," Ten Hag said. "The start was very good, exactly how we planned it. We scored a great goal and in the second half we were proactive and scored two goals. We're taking positives from it. We had problems at the start of the season. A lot went against us. We're growing. We have to keep this process growing."

It was Everton's first game since news broke of their 10-deduction for breaching the Premier League's financial rules, and after thousands of supporters joined a protest outside the stadium the atmosphere had reached fever pitch by kickoff. Fans booed the Premier League signage as it was walked onto the pitch for the team lineups and fans held up thousands of pink placards featuring the league's logo and "corrupt" written underneath. Sean Dyche said in the buildup he hoped the anger would galvanise his players but with just three minutes on the clock, the energy was drained from the stands by Garnacho's moment of magic.

It was a goal so good that it will be shown in replays forever. For a second it looked like Diogo Dalot had overhit his cross, but Garnacho first backpedaled and then arrowed a bicycle kick into the top corner. Think Wayne Rooney against Manchester City; the type of goal that shouldn't really be humanly possible and so takes a split-second to absorb. By the time it had sunk in, Garnacho was halfway through his Cristiano Ronaldo "Siuuu" celebration.

Ronaldo, who scored United's winner here last season, would have approved.

"It was a fantastic goal and this season still many games to play but probably already the goal of the season," Ten Hag said. "Not only the finish, it was the total from the back to the end. The finish was incredible, world-class. It was a magnificent moment."

As good as the opening goal was, it didn't stop United from showcasing their usual frailty for the rest of the first half. For a while after Garnacho's strike, the stadium sat in a sort of stunned silence but then Everton began to play and for the last 15 minutes it was chance after chance.

Dominic Calvert-Lewin had two headers, one saved by André Onana and one over the bar, and Abdoulaye Doucouré somehow missed the target from 10 yards. Idrissa Gueye skewed a shot high and wide and amid wave after wave of Everton attack, Mainoo blocked a shot from Dwight McNeil and cleared another effort off the line.

Depending on how you want to look at it, it was either impressive or frightening that Mainoo, a teenager making his first start in the Premier League, was the most composed man in a red shirt despite being surrounded by expensive, experienced internationals.

"He has a lot of abilities and it was a really disappointing moment in preseason when he got so badly injured," Ten Hag said. "I know he can progress a lot if he plays many such games as today. Players will develop very quickly and we thought it was the moment to bring him in. He's a good boy, very mature, and he showed it."

Fortunately for Ten Hag, who said afterwards he had handed out some harsh criticism to his players at half-time, Mainoo's calmness seemed to spill over into his teammates in the second half and when Ashley Young was adjudged to have tripped Martial in the box following a VAR check, Rashford scored from the spot to put United up 2-0 in a league game for the first time this season.

A flowing team move was finished off by Martial -- in the starting XI for the injured Rasmus Hojlund -- to make it 3-0 and give the scoreline a more comfortable look than perhaps it deserved. But Ten Hag won't care and neither will Garnacho and Mainoo, who might have United finally moving in the right direction.