Johnson has named a squad of 13, bringing Nick Beard in from injury and with Blair Soper waiting for a debut, and will make the final call this morning.
"We've got a couple of niggles to check, so we've picked 13 and we'll just decide when it's time," Johnson said.
Beard is available for selection after recovering from a shoulder injury sustained in a pre-season game and a virus.
Rising fast bowler Soper will be keen to unleash his pace and youthful vigour as a ready-made replacement for Black Cap Neil Wagner.
Otago has to be pleased about playing Canterbury again so soon.
The two sides have played a lot of cricket against each other in the past month and the Volts have been dominant.
In mid-October, they outplayed Canterbury in a two-day warm-up game and then met in the opening Plunket Shield late last month, with Otago winning by eight wickets.
A couple of key players from that match will be missing, of course.
Otago loses Wagner and Canterbury will be without Todd Astle.
Both are joining the Black Caps in Sri Lanka for the two-match test series and will be sorely missed.
Wagner took eight wickets and Astle had a nice double with the bat, scoring 95 and 78.
Wagner's absence will be felt keenly as strike bowler James McMillan (ankle) and all-rounder Sam Wells (hamstring) are both ruled out.
"Neil is a real key part of our attack and he is a big loss," Otago captain Derek de Boorder said.
Otago opener Aaron Redmond is probably more excited than any of his team-mates at the prospect of another bat against Canterbury. He returned to form with back-to-back 100s in the eight-wicket win but then missed out against Northern Districts with just one run from two innings.
Neil Broom scored an undefeated innings of 146 to ensure Otago held on for a draw with Northern, and Jimmy Neesham posted his maiden 100 in the first innings.
Michael Bracewell (88 not out) and Hamish Rutherford (91) have also posted significant scores, so confidence in the batting line-up should be high.
However, the bowling could come under pressure. In the opening game against Canterbury, Wagner and McMillan were both injured on the third day and Canterbury was able to score more than 300 runs for the loss of five wickets.
Eighteen-year-old Jacob Duffy is still making his way in first-class cricket but with Wagner and McMillan unavailable, he is suddenly thrust into the role of Otago's spearhead.
Ian Butler is likely to partner Duffy with the new ball. He bowled well in Northern's first innings with four for 39 but struggled to make an impact against Canterbury.
The University Oval has proven to be a helpful venue for the seamers and the toss is usually followed by a quick decision to field. In the last 10 first-class games at the venue, the team which has won the toss has elected to bat just once.
But there have also been 27 centuries scored in 31 first-class games. Earlier this year Rutherford broke the ground record with his innings of 239.
Auckland has taken a commanding lead at the halfway point of its Plunket Shield match against Northern Districts thanks to a record seventh-wicket partnership, APNZ reported.
After bowling out the visitors for 208 on Saturday at Eden Park's outer oval, Auckland looked to be stuttering its way towards a similar score when it was reduced to 150 for six.
But that brought No 8 Bruce Martin (107 not out) to the crease where he joined Craig Cachopa (82) in an unlikely 168-run stand to leave the Aces with a lead of 157 at stumps and three wickets still in hand.
Otago v Canterbury
University Oval, starts today
Otago: Aaron Redmond, Hamish Rutherford, Michael Bracewell, Neil Broom, Darren Broom, Derek de Boorder (captain), Jimmy Neesham, Mark Craig, Ian Butler, Jacob Duffy, Blair Soper, Nick Beard, Iain Robertson.
Canterbury: George Worker, Peter Fulton, Shanan Stewart, Dean Brownlie, Henry Nicholls, Brad Cachopa, Ben McCord, Matt McEwan, Cole McConchie, Willie Lonsdale, Tim Johnston, Will Williams.
