Surface plasmon polaritons (briefly, plasmons) are particular electromagnetic waves localized in a narrow region at the interface between two different media, e.g. a metal and vacuum. Plasmonics exploits these waves for a great number of advanced applications in optics, sensors, electronics and source developments. Ultrafast plasmonics pushes these applications to the femtosecond regime. In a paper on ACS Photonics, we test by simulations a proposals to generate an extremely short plasmon - less than two field oscillations long, that corresponds to less than 4 fs. The proposal is based on the well known technique for resonant plasmon excitation by the incidence of a laser pulse over a metal with periodically modulated surface (grating) at an angle determined by the grating pitch. By introducing a rotation of the laser wavefront, which is equivalent to change the incidence angle with time, the resonance holds for a brief interval so that an plasmon much shorter than the laser pulse is generated.