Frustrated Vettel looking over his shoulder at Red Bull

MONACO (AP) Ferrari driver Sebastian Vettel started the Formula One season with high hopes of challenging dominant Mercedes. Instead, the four-time F1 champion is behind his own teammate Kimi Raikkonen and looking over his shoulder at resurgent Red Bull.

The German is in fourth place after five races, trailing championship leader Nico Rosberg by 52 points and second-placed Raikkonen by 13 - having ended last season well clear of Raikkonen in the standings.

Vettel, who finished third overall last year, is level with his former Red Bull teammate Daniel Ricciardo, with Red Bull's teen driver Max Verstappen only 10 points behind them.

Vettel's first season with Ferrari in 2015 saw him win three races, a welcome boost following a hugely disappointing final year with Red Bull where he was outperformed by Riccardo.

It has been a complicated season so far for Vettel - who failed to get any points in Bahrain and Russia - and missed an opportunity to win two weeks ago at the Spanish GP when Mercedes drivers Lewis Hamilton and Nico Rosberg crashed into each other and out of the race. Vettel finished third in Barcelona, while the 18-year-old Verstappen became F1's youngest race winner.

''We had the chance to win, yes, but that is all past,'' Vettel said. ''I still find it an amazing achievement that somebody jumps into a car for the first time and wins. It sure was a fantastic moment for him (Verstappen) and well deserved.''

Vettel says he is ''not really'' surprised by Red Bull's improved speed and predicts that ''they will also be strong in qualifying'' on Saturday.

Although generous with his praise, Vettel's frustration is evident to see and is even spilling onto the track.

In Thursday's practice, racing fans had the unusual sight of Vettel's trusted Ferrari twice hitting the track-side barriers when he was under no pressure.

''I banged the wall here and there, so of course I am not satisfied,'' said Vettel, who has 42 career race wins but none in the past 11 races. ''This is a track where you tend to try everything and sometimes you try too much.''

Vettel has won Monaco only once, on his way to a second straight F1 title with Red Bull in 2011. Since then, he has twice finished runner-up, retired from the race two years ago and finished fourth in 2012.

''We are not here to fight for P8 (eighth place) or something in that range, we want to win,'' a defiant Vettel said ahead of qualifying. ''We should be significantly stronger on Saturday. In an ideal world we will be right on the front row.''

SI Apps
We've Got Apps Too
Get expert analysis, unrivaled access, and the award-winning storytelling only SI can provide—from Peter King, Tom Verducci, Lee Jenkins, Andy Staples, Grant Wahl, and more—delivered straight to you, along with up-to-the-minute news and live scores.