He declined to say who was in line for a rest but it is fair to say there are plenty of options.
The Volts are winless after four games and will need to win to keep their slim playoff prospects alive.
While Mascarenhas was reluctant to single out any of his players, Otago's death bowling has been a major weakness.
In the record 106-run loss to Auckland on Saturday, Otago conceded 89 runs in the last five overs.
Overseas professional Dirk Nannes was the worst offender.
His four-over stint cost his side 59 runs and 29 of them came off the last over.
Jacob Duffy has also struggled since returning from an ankle complaint.
Together they are the most expensive bowlers in the tournament.
Nannes has the No 1 spot conceding 11.43 runs an over.
Duffy is in second place at 10.77.
Fellow pace bowler James McMillan has to settle for fourth place at 9.80.
Jesse Ryder is at the other end of the list. He is the most frugal bowler in the tournament, going for a miserly 3.37 runs.
Oddly, he has not been required to bowl his allotment of fours in any of Otago's four losses.
Mascarenhas defended the bowling plan but not the bowlers.
''They are just not executing it. Is as simple as that,'' he said.
''Realistically, we should have won three games and lost one but we've lost them all. We're close; we just need to execute better at the crucial times and when it matters.''
Mascarenhas said the decision to bowl Nannes and Duffy at the death was a set plan.
''They are our two best bowlers at the death but they have not been doing that at the moment.
''Jesse has been going well up front. The spinners have worked a treat in the middle. It is just the back end which has not quite clicked yet.
''But, in saying that, the batting has not been exceptional either. We've only had one 50 and that was in the last game. They have to lift as well.''
Nannes occupies one of the import slots and has not delivered on his potential.
But Mascarenhas said Otago was not considering replacing him.
''By his own admission, he has under-performed and he needs to get better. I think it is just a lack of bowling before he got here.
''He is getting into his work now and will hopefully be able to fire on Thursday for us.
''He has had a good net this week and is looking good.''
