The judge who will decide whether a state senator intentionally slashed his girlfriend’s face after a two-hour altercation heard two very different interpretations of the same events yesterday, as opening arguments began in the felony assault case.

In the prosecution’s version, Senator Hiram Monserrate, D-Queens, 42, sought to assert his “power and control” over girlfriend Karla Giraldo, now 30, when, on Dec. 18, 2008, he smashed a glass and cut Ms. Giraldo near the eye in a fit of “jealous rage” because she had another man’s police union card that contained a cell phone number.