McLaren have reportedly made initial steps to see how viable a switch to Mercedes power units could be after its F1 pre-season testing nightmare with current partner Honda.

With Honda being hit by an unreliable and uncompetitive power unit at the start of 2017 and just two weeks to turn around its fortunes in time for the season opener in Australia, many are forecasting another frustrating year for McLaren.

According to the BBC, McLaren are believed to be assessing its options if Honda cannot solve its issues and the relationship turns sour, with Mercedes seen as the primary candidate to be the replacement engine partner.

At the end of pre-season testing at Circuit de Catalunya-Barcelona, McLaren racing director ruled out the option of ditching Honda as its engine partner which would require a breakout from its current contract that began in 2013 along with a major financial reshuffle.

Honda currently supplies McLaren engines for free in a deal which earns the Woking-based team a reported $100 million annually, while opting for a new customer engine package would cost a minimum of $18.5m per year.

With the Japanese manufacturer paying out for half of McLaren's driver salaries plus significant sponsorship commitments the team would require a vast overhaul in its funding plan by its major shareholders.

Mercedes has said it's open to the prospect of supplying engines to more teams on the F1 grid but for McLaren it looks a difficult U-turn to pull off after splitting from the German manufacturer as a customer team in 2013 after a 20-year partnership with a soured relationship as Mercedes set-up its own factory team in F1.

However, McLaren appears to be losing confidence in Honda's ability to produce a competitive power unit after the latest problems with its revised engine configuration for 2017 which saw the MCL32 be unreliable and uncompetitive during pre-season testing.

Last week, Boullier said he felt McLaren could win if it had Mercedes engines and the team is worried about losing star driver Fernando Alonso who desires a race-winning car and publicly criticised Honda while testing in Spain.

READ: Alonso shoots down 2015 McLaren-Honda comparisons

Latest Tweets from Crash.net & GPF1rst