Edoardo Molinari birdied his first six holes and finished with another to charge into the lead at the Volvo Golf Champions in Bahrain.
Resuming only joint 14th after an opening 68, Molinari added a 65 to reach halfway on 11 under par.
That was two in front of his brother and Ryder Cup partner Francesco and also overnight pacesetter Johan Edfors, although the Swede was among the later starters in the second round.
Edoardo was delighted by his position - and also the fact that his brother was in contention. Francesco was a playing partner in the final round when he won both the Barclays Scottish Open and Johnnie Walker Championship last season.
"It's good fun," he said. "It was quite windy at first and so it was a great start obviously.
"I quite like funny courses. This is not straightforward - you have to plan your way round and be patient.
"It was a little bit frustrating in the middle. I had a lot of chances and was not putting very well, but it was good to end with a birdie."
Francesco, the higher-ranked of the two Italians by four spots at 15th in the Official World Golf Ranking, followed up his first day 66 with a 69 and said: "Hopefully I can catch him."
His wife Valentina is expecting their first child in three weeks time.
Padraig Harrington got further than he did last week in Abu Dhabi when a disqualification followed his opening 65, but the three-time Major winner remained six shots off the pace with a 69.
Edfors bogeyed the eighth, but closed the gap to one with birdies at the next two, while Argentina's Ricardo Gonzalez went to the turn in 31 and started for home eagle-birdie to be eight under for the day and nine under the tournament.
Sergio Garcia dropped his first shot of the week at the short seventh but three birdies in a front-nine 34 left him still very handily placed at seven under like Paul Casey.
France's Raphaël Jacquelin, who moved to seven under for the day with the par five ninth still to come, and Edfors made it a three-way tie at the top on 11 under, but the Swede followed with a double bogey six on the 15th.
He instantly dropped to seventh as four players - Casey, Sweden's Peter Hanson, Spaniard Alvaro Quiros and South African James Kingston - all improved to ten under with the closing stretch yet to play.
