Michael Carrick’s Red Devils have already travelled over to Lombardy, the region that is home to Serie A club Como. Authorities have issued an orange weather warning, with the Servizio Meteorologico forecasting heavy rain and thunder to last throughout Wednesday until 2am local time on Thursday morning.
Kick-off is scheduled for 6:45pm local time (5:45pm BST) on Wednesday evening, at which time there is expected to be thundery showers, wind and a risk of lightning.
According to the Italian government department Protezione Civile, an orange alert “indicates a potential dangerous situation.”
The wet weather started on Tuesday morning and has shown no signs of abating, leading to concerns as to whether Como and Manchester United will be able to play the third game of their respective Champions League campaigns.
Man Utd boss Carrick did not appear to be concerned about the game possibly not going ahead during his pre-match press conference on Tuesday night.
Asked if he was worried about the match being called off, Carrick replied: "No, nothing immediate from me, we're used to the rain. We'll make the most of it.”
Only one of the four stands at Como’s 12,039-capacity Stadio Giuseppe Sinigaglia is covered, meaning that if the game goes ahead, fans in attendance are set for a soaking.
The last time a Champions League game was postponed due to weather was all the way back in September 2016. Manchester City saw their Group C clash at home to Borussia Monchengladbach rearranged after heavy rain, thunder and lightning hit.
Originally slated for a Tuesday kick-off, the game was pushed back to Wednesday, when City eventually cruised to a 4-0 win over their German visitors.
Currently enjoying their debut Champions League campaign, Como - managed by former Arsenal, Chelsea and Barcelona midfielder Cesc Fabregas - thumped German side RB Leipzig 4-1 at home before losing a thriller away at Feyenoord, 3-2.