The latest measurement of the muon g-2 announced at Fermilab exhibits a 4.2$\sigma$ discrepancy from the currently accepted Standard Model prediction. The main source of uncertainty on the theoretical value is represented by the leading order hadronic contribution $a_\mu^\text{HLO}$, which is traditionally determined through a data-driven dispersive approach. A recent calculation of $a_\mu^\text{HLO}$ based on lattice QCD is in tension with the dispersive evaluation, and weakens the discrepancy between theory and experiment to 1.5$\sigma$. An independent crosscheck of $a_\mu^\text{HLO}$ is thus required to solve this tension and consolidate the theoretical prediction.
The MUonE experiment proposes a novel approach to determine $a_\mu^\text{HLO}$ by measuring the running of the electromagnetic coupling constant in the space-like region, via $\mu-e$ elastic scattering. The measurement will be performed by scattering a 160 GeV muon beam, currently available at CERN's North Area, on the atomic electrons of a low-Z target. A Test Run on a reduced detector is planned to validate this proposal. The status of the experiment in view of the Test Run will be presented.