Australian batsman Chris Rogers is to take over the captaincy of Middlesex for the team's First Division County Championship matches while regular skipper Neil Dexter tries to regain batting form.
Dexter, who took over as captain at Middlesex in 2010 and guided the team to the Second Division title in 2011, will remain club captain and will lead the Lord's-based side in this season's one-day county competitions.
Rogers led the side for the last three games of Middlesex's promotion campaign when Dexter was out injured with a broken finger.
Middlesex cricket director Angus Fraser, in a statement issued Wednesday, said: "Once again I applaud Neil for his selfless and honest behaviour.
"I selected Neil as Middlesex captain in 2010 because of the standards and values he holds, and he never lets you down," the former Middlesex and England seamer added.
"Neil's captaincy during the thrilling three run victory over Surrey was outstanding. It played a major role in turning potential sorrow in to delight."
Dexter managed just one run in two innings in Middlesex's thrilling derby win over their London rivals and Fraser said: "He is, however, not happy with his current form with bat and believes extra time spent concentrating on this part of his game will help return him to his best quickest, which is what we all want.
"Once Neil's form returns, as it inevitably will, and he is happy with where he is at the captaincy will return to him."
Turning to Rogers, Fraser said: "Middlesex are extremely fortunate to have a player of Chris Rogers standing as back-up.
"Chris captained the team very well at the end of the 2011 season and his happy to stand in to help the team's cause.
"Chris is fully aware of the situation. He knows that the job is Neil's once he and the Club feel the time is right."
Rogers, 34, made the only Test appearance of his career to date against India in Perth four years ago, scoring four and 15 in two innings at the WACA.
He has though proved a consistently heavy run scorer at county level.