Last week's Abu Dhabi winner Paul Casey made an indifferent start, carding a par 72, while Ireland's Paul McGinley finished at one under.
With only nine players in the 54-strong field under par, the Ryder Cup trio of Paul Casey, Padraig Harrington and David Howell are firmly in contention on level par.
Mickelson ended alongside Ernie Els, Dustin Johnson and Ryo Ishikawa with Paul Casey in a group at even par.
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Westwood produced a solid one-under-par round to stay in contention at nine under par overall while fellow Englishman Paul Casey is a further shot back.
Two Paul Warwick penalties were all under-par Munster could manage.
Defending champion Casey, meanwhile, ended the week on 19 under par after his 68 while Ireland's Paul McGinley - who lost in a play-off last year to his Ryder Cup team mate - was three shots further back after a 70.
Darren Clarke and Paul Casey also hit rounds of 68 to move to 10 under while Paul McGinley is seven under for the tournament after a one-under-par 71.
Driscoll, meanwhile, shook things up with an eight-under-par round of 62 to take the clubhouse lead at 15 under par before Johnson forced sudden death having led by two shots from Paul Goydos after 54 holes.
Englishman Ross Fisher shot a 69 and Scotland's Richie Ramsay a 71 as they joined Ernie Els in a tie for fourth place on eight under par, with Padraig Harrington two further back and England's Paul Casey moving up to five under with a 67.
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Paul Lawrie, Stephen Gallacher and Colin Montgomerie all finished one better off than Drysdale on six under par for the week.
There was, however, disappointment for a host of big names, including Nick Dougherty, Scott Drummond, Paul Lawrie, Paul McGinley, Colin Montgomerie, Henrik Stenson and Lee Westwood, as they all missed the weekend cut at even par.
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