Not even the hometown fans will be able to give Rubens Barrichello enough of a boost to make him a top contender at IndyCar\'s Sao Paulo 300 this weekend. Barrichello is thrilled to be racing in front of his Brazilian fans for the first time since joining IndyCar, but admits he still is adapting to the series and won\'t be racing among the leaders on Sunday, local time. The Formula One veteran said that despite racing at home, he will be facing the same difficulty he encountered in his first three races of the season, when his best finish was an eighth place in Alabama. He said his unfamiliarity with the challenging circuit on the streets of South America\'s biggest city will leave him at a disadvantage over most of the field. \"My biggest problem is not knowing the tracks, that has given me the most difficulties so far,\" Barrichello said. \"That\'s going to be the case again here in Brazil. The only advantage I\'ll have here is mental, the advantage of being at home, of wanting to perform well to the fans. But the difficulties will be the same as before.\" Barrichello tested well before the season, but was not able to finish near the front in his first three races. He opened his season with a 17th-place finish at St. Petersburg after a mechanical problem, then was eighth in Alabama and ninth in Long Beach after starting 22nd. \"I\'m still not 100 per cent comfortable with the car, I need more time, it\'s completely different from what I used to drive in Formula One,\" he said. \"I\'m being able to show some improvement during the races because I\'m learning the tracks as the race progresses.\" The 39-year-old Barrichello said he expects even more difficulties in Sao Paulo because the track will only open to drivers on Saturday. Drivers usually can start racing Friday on non-street circuits. A plus for the popular driver is that he will be allowed to have some extra time on the track and an extra set of tyres because IndyCar changed his status to a rookie before the Long Beach race two weeks ago. He also will have a new engineer in Sao Paulo after KV Racing hired Eddie Jones, a former Andretti Autosport employee. Jones was with the late Dan Wheldon when the British driver won the 2005 Indy 500. Barrichello said he is trying to stay optimistic despite the expected challenges he will face in Sao Paulo. He knows that weather has played a significant role in the race in the past, providing plenty of opportunities for drivers to try to come from behind to contend. The F1 veteran gained even more confidence after having a good car in Long Beach, where he started back in the grid and charged to the front on a track similar to the one set up on the streets of Sao Paulo. \"I\'m always thinking positive, especially here in Brazil,\" he said. \"I\'m hoping for a good weekend.\" Barrichello is ninth in the drivers\' standings with 59 points, 68 behind series leader Will Power, who won the first two races in Brazil in 2010 and 2011. Barrichello is ahead of his two KV Racing teammates friend and fellow Brazilian driver Tony Kanaan and Venezuela\'s E.J. Viso, who are tied for 11th with 54 points. Barrichello joined IndyCar this year after losing his seat with Williams in F1, where he raced for a record 19 years. He is hoping to repeat the success of other F1 drivers who made the move to the U.S.-based series. F1 champion Nigel Mansell joined CART in 1993, winning five races and the title. Emerson Fittipaldi thrived in the late 1980s and early 1990s, winning the series once and the Indy 500 twice. Fittipaldi, also a Brazilian, won the F1 championship in 1972 and 1974. Barrichello is the biggest name to move to an American-based open-wheel series since Mansell. The Brazilian finished second in the F1 drivers\' championship in 2002 and 2004 with Ferrari, both times behind seven-time champion Michael Schumacher. He won 11 races in F1, but none in Brazil, where his best finish was third in 2004. He earned three pole positions when racing at home, two with Ferrari in 2003 and 2004 and one with Brawn GP in 2009. \"The only thing I can guarantee is that I\'ll be giving my best this weekend,\" Barrichello said. \"Let\'s just see what happens.\"