Smoke cannons blasting off behind the goal, live music bursting out from a DJ set during corners and free shirts being thrown to fans at half-time - this was not the usual experience Europe's top female footballers are accustomed to.

"Carnage. Just chaos," said Manchester United manager Marc Skinner, fresh from his side's 3-2 win over Roma in Portugal.

The Women's World Sevens kicked off in Estoril on Wednesday with Manchester United and Manchester City among the eight clubs involved.

The new seven-a-side competition has a prize money pool of $5m (£3.76m) - more than what the Women's Champions League winners will earn three days later in Lisbon.

With rolling substitutes, no offsides and 15-minute halves, it's a format that brings out flair and creativity, as well as attacking intent.

England international Jess Park began lighting things up when she nutmegged a player to earn a corner, prompting the DJ as she prepared the set-piece in Manchester City's opening 4-0 win over Rosengard.

United duo Celin Bizet and Grace Clinton took the fun to another level shortly afterwards, chest bumping in celebration after England midfielder Clinton's clever chip drew gasps from the 200-odd fans watching on in the stands.

By the time Bayern Munich came on, beating Ajax 4-2, players were full of fun and energy - Norwegian defender Tuva Hansen even whipping off her shirt to celebrate in Chloe Kelly style after scoring a rare goal.

"I really enjoyed it. I think the Roma players took it a bit more seriously than us! We had loads of fun," said United's Clinton.

"We've all come here as a team. We didn't really know what to expect. This is what we want to do in training every day. We really embraced it.

"It's a lot more high-intensity but also free. It's very unpredictable because you don't know where the ball will go. It's more enjoyable I would say."

Games are being played at the Estadio Antonio Coimbra da Mota - a 5,000-capacity ground in Estoril - but it was transformed for the World Sevens.

From 20:30 BST on Saturday, following Estoril men's 4-0 win over Estrela, stands were built, TV cameras put in place and large screens put up.

The match schedule was shuffled after United's men reached the Europa League final - which they lost 1-0 to Tottenham on Wednesday - so Skinner's side played earlier at the World Sevens to avoid a clash.

Fans initially came in slowly, with little more than 100 watching City's win over Rosengard, but alcoholic drinks were flowing as more came throughout the night, filling a stand on the far side before Paris St-Germain's 2-1 win over Benfica.

"It is interesting. It is something different. The stadium looks nice," said City fan Leanne Woodall, who travelled out to Estoril.

Fan Charlotte Wilkins added: "I play seven-a-side football so I was really excited to see how the professional players did it and the tactics they used.

"We couldn't find where we needed to go when we first got here, but now we're in, it's really good and there's good vibes so far. It's exciting."

Organisers hope to fill the arena on Friday when the semi-finals and final will be played and more fans fly out to Portugal in anticipation of Saturday's Champions League final between Barcelona and Arsenal (17:00 BST).

But first impressions from the players were certainly positive.

"It was so nice, I was really sad it was only one game today, I could play all day like this," said Roma's Hawa Cissoko.

"I think we took the game a bit more seriously at the beginning than Manchester United, they arrived on the pitch really [relaxed].

"Them doing this made me think 'we are here to have fun'. We were doing this when we were kids. It makes me feel a bit like [I did] 10 years ago. That's so nice."

Manchester City interim manager Nick Cushing said the style of football was how they "believe the game should be played".

Brazil forward Kerolin added: "I liked a lot the music. In Portugal the weather is really nice so everyone is like 'OK, we like these vibes'.

"Of course we want to win and get some money! But it's a little bit Brazilian I think. I like the ginga [an informal Brazilian term for expression of creativity with agility and trickery].

"I want to get back those things and be a little bit brave. Today I was a little bit unsure - but it will come."

Clubs' participation in the tournament has been controversial, with some questioning the timing and the risk of injury with Euro 2025 starting on 2 July.

Rosengard face BK Hacken in the Swedish league on Saturday (14:00 BST) but travelled to Estoril to take part.

"We had some reactions in Sweden, that we came here, because we have a game," said Rosengard midfielder Emelia Larsson.

"For us, it's like taking a break from all of it. You miss a training week, but if you put that aside, I think it's just really fun to be here.

"It's a good opportunity to show ourselves and show Swedish football."

Manager Joel Kjetselberg said it was good practise to prepare for Champions League football, for which they would travel midweek, in between weekend matches.

City held around five training sessions to prepare for the World Sevens, while United had one.

"We would only be doing this in training all week anyway," said United's Clinton.

"If we were going into the next England camp, we would all have just been doing small-sided games anyway.

"This is probably a better outcome and gives us more fitness."