Dutchman Seip returned to the Argyle side for Saturday's 1-0 win at leaders Wolves following a groin injury which has ruled him out since January.
His return meant Chris Barker could move back to left-back in the absence of Gary Sawyer, who was ruled out by an ankle injury.
Saturday's match also marked the debut of teenage striker Ashley Barnes, who replaced Rory Fallon as targetman, while Chris Clark was recalled on the left side of midfield.
Nineteen-year-old Barnes is set to continue up front as Argyle look to move clear of Watford in the table.
Watford manager Brendan Rodgers has a doubt over captain Jay DeMerit.
The American defender limped off after just 57 minutes of Saturday's 2-0 win over rivals Crystal Palace after suffering a calf strain.
DeMerit's withdrawal was only a precaution but should he fail to make it Jon Harley, who replaced him at the weekend, or Gavin Hoyte could come into the starting line-up.
However Rodgers is boosted by the return of striker Tamas Priskin after he missed the Palace clash with a one-match ban.
Goalkeeper Mart Poom is still sidelined with a shoulder injury while midfielder Gareth Williams has a continuing knee problem and it is uncertain when the experienced duo will return.
Sporting Life