Formula 1's tyre supplier has brought the medium and hard compound to this weekend's race at Sakhir, having originally intended to use the soft and hard compound for round four of the 2013 Formula 1 world championship.
However, having seen how its new more aggressive compounds reacted in the opening two grands prix, the Italian company elected to change its plans in the days after the Malaysian race.
It believed that with teams having experienced high degradation at Sepang, it would be better at the abrasive Bahrain circuit to use its most conservative choice.
The decision to use the medium instead of the soft was communicated to the teams before the Chinese Grand Prix - a race that fuelled intense debate about the impact tyres are having on F1 racing this year.
News of the change of compound choice was only made public earlier this week.
Pirelli is also awaiting a decision from the FIA and teams over its proposal for teams using rookies in free practice to get an extra set of tyres, as revealed by AUTOSPORT.
It is hoped the matter will be voted on over the Bahrain GP weekend.
This week's AUTOSPORT magazine features a hard-hitting column from Pirelli's Paul Hembery on his company's approach to F1 2013