His excellent displays follow a summer in which the Sao Paulo-born playmaker secured his first senior success in a Brazil shirt, helping his side to a memorable victory at the Confederations Cup. Having played a major role in the Selecao's Under-20 World Cup victory in 2011, his status in the Brazilian game is undisputed.
However, Oscar's route to the top has been far from easy. From a difficult upbringing to contractual disputes with his first professional club, the 22-year-old has already come through considerable adversity to reach the top of the game.
A difficult childhood
The cliche of Brazilian footballers is always that they have battled their way out of a drug-riddled favela to make it to the top of the game. While that is far from the case for many players, it does not necessarily mean that they have had an easy upbringing.
Oscar lost his father in a traffic accident at the age of three, leaving his mother to bring up three children in Americana, Sao Paulo—having been pregnant with Oscar's younger sister Gabriela at the time of the accident.
Last year, Oscar spoke of the pain of growing up without his father to Globo Esporte (Portuguese): "Of course I don't remember him," he commented. "But, you miss your father when you are playing football. All the parents are there, but yours is not there."
In a separate Globo Esporte interview, the playmaker played down the difficulty of his childhood, paying tribute to the contribution of his mother, Sueli.
It's not that it wasn't easy, I was happy there. I liked it a lot living in the "interior" (Sao Paulo state, away from the city of Sao Paulo itself.) I lost my father when I was three. It's difficult, but I don't remember [him]. I would like my father by my side, that he could see my play. However, it happened. My mum looked after me and my sisters well.
Sueli was left to raise Oscarzinho, as he was known, making money by making and selling clothes in the family's hometown as she explained to Globo:
His father left me a house to live in, but I had to work by myself. I couldn't work for a company because I needed to stay with them. I would take clothes to sell and we worked through it. It is not easy for just a woman and her husband these days—imagine being alone with three children.
Oscar's footballing talent, though, began to show through at an early age, and by 12 years old, the young Brazilian had joined the youth ranks of club side Ipiranga. Soon after, he would join the youth ranks of Sao Paulo.
An early dispute at Sao Paulo
Oscar's senior career began at the age of 17, when he made his debut for Sao Paulo in 2008. It was in 2009, though, that he would really come to the fore following an impressive campaign at the Copa Sao Paulo youth tournament in January where he scored three goals.
Head Researcher for Football Manager in Brazil Paulo Freitas had this to say to B/R about Oscar's time at Sao Paulo:
"Oscar was always regarded as one of the 'jewels' in Sao Paulo's youth academy. He made his debut in 2008, but started shining in 2009, making an assist in a game versus Corinthians in June, after also getting praise from Muricy Ramalho, who called him a 'classic No. 8.'
"However, his spell at Sao Paulo was quickly overshadowed by his disagreement with them over his contract renewal, which lead to take his situation to court, he eventually moved to Internacional."
The No. 8 that Ramalho spoke of is an interesting role that can take on a variety of meanings. However, in Sao Paulo's 3-5-2 formation of the period, it was very much the domain of the second attacking midfielder.
Oscar won 6 tackles against Fulham, more than any other player in either Chelsea or Fulham's side. An unexpected grafter. #CFC— Squawka Football (@Squawka) September 21, 2013
Oscar had always been regarded as a central playmaker, or No. 10. However, Ramalho saw Oscar as a more rounded player who could contribute defensively from his attacking midfield role—a dimension to his game that has seen the Brazilian appeal to Jose Mourinho this season.
His time at Sao Paulo may not have lasted long, but his potential was clear.
Rise to the top of Brazilian football
Moving to Internacional late in 2010, Oscar began his rapid ascent to the top of Brazilian football that would see him make his international debut less than a year later.
A versatile attacking player, Oscar became an integral member of the Internacional attacking unit early in the 2011 season. He was predominantly used as a second striker, with Andres D'Alessandro taking the lead in terms of creative responsibility and the talented Andrezinho lining up alongside him in attacking midfield.
Oscar, though, would play a variety of roles over the season, linking well with forward Leandro Damiao to score 10 league goals and also help his striker to double figures.
The season, though, would be marked by a standout performance at the Under-20 World Cup. Oscar had formed an excellent midfield understanding with the central duo of Casemiro and Fernando, allowing Philippe Coutinho to take on the No. 10 role for the side.
In the final, though, it was Oscar who added to an already impressive tournament with a spectacular hat-trick to seal the title for the Selecao.
It was that moment that sealed the young attacking midfielder's place within the Brazilian hierarchy, earning him a senior call-up just a month later. Just as he took on an ever more important role with Internacional as teammates departed, so his integration in the Brazil squad increased.
His continued rise came to a head in 2012, when Oscar assumed the No. 10 shirt and a central role in Brazil's side at the London Olympic Games. Neymar may have been the star heading into the competition, but it was the soon-to-be Chelsea star who would end the tournament as Brazil's leading light.
Becoming an integral player At Chelsea
Oscar joined Chelsea in July 2012, per BBC Sport, shortly ahead of the Olympic Games for a fee of around £25 million.
Having arrived late at his new club following the Olympics, the Brazilian was set to be eased into the Blues lineup. However, on his first start for the club, Oscar sensationally scored twice in a Champions League clash with Juventus.
While that would be an early highlight of a season in which he gradually eased his way into life in the Premier League, the attacking midfielder was by now already taking on a major role with the Brazil side.
"I am going to emphasise his personality," said Pele, the most famous holder of Brazil's No. 10 shirt, to Globo Esporte. "Romario, with all his reputation, did not want to play wearing 10—he played with 11. Oscar has taken it on."
While his courage cannot be faulted, the player himself has been quick to admit that he sometimes needs to assert himself more on matches—a fault which has been levelled at him in his time in England.
"On the field, sometimes it even forced my friends to say something," he admitted in the same Globo interview. "'You need to talk! Ask for the ball.'
"It's my way, I am quiet and I think I am similar on and off the pitch. You have to see me and pass. If I am free, pass. It's difficult for me to ask."
However, with one season under his belt, the Brazilian already looks a much more confident player, having already scored three goals this season—a campaign in which he has arguably been Chelsea's best player to date.
Entrusted by Mourinho to be his No. 10, Oscar has taken over the reins from Juan Mata at the heart of the Chelsea attack. The Blues may not be firing on all cylinders yet, but the Brazilian certainly cannot be faulted for his impact.
Mourinho is believed to like the defensive responsibility that Oscar shows while also conducting the side's attacking play. They are the same all-round qualities that Ramalho referred to early on in his career and, ultimately, are the same attributes that have made Oscar crucial to Luiz Felipe Scolari's Brazil side.
The Brazilian, having turned 22 only this month, is only set to improve as he learns to assert himself more on Premier League encounters.
A wonderfully gifted player, he is already well en route to becoming one of the Premier League's leading lights, and over time, he will surely play a crucial role in many Chelsea successes.