First off – we have to accept at the outset that the most noteworthy piece of clothing at Old Trafford on Wednesday night was worn by RB Leipzig manager Julian Nagelsmann, but unfortunately it doesn’t come under the ‘kits’ heading.
The last time Leipzig played a Champions League game in England, they had a sponsor mix-up (possibly intentional, if we’re being cynical) and while this post isn’t about anything as remarkable, it’s nevertheless an insight into Uefa’s kit-selection management.
Had both home strips been used (we’re assuming that Manchester United’s first-choice kit for European competition includes white socks, as is generally the case), there would have been an overall-clash issue and Leipzig’s red change socks wouldn’t have done much to solve it:
They could have played in their away kit, but instead Uefa applied what we might term a World Cup approach, with both teams changing shorts and socks so as to increase the differentiation. In Leipzig’s case, that meant third-choice socks, similar to how Arsenal were affected in the 2017-18 Europa League.
It’s not completely unknown for a home team to change elements in such a way in Europe – United wore red-black-black against the all-white of Milan in 2004-05, though two years later they were able to wear red-white-white with Milan in white-black-black.
Oddly, their socks were not the domestic home socks, which have the ‘Manchester United’ wordmark, but instead one with only the adidas logo. It’s not that Uefa prohibit the wordmark, which appeared on the white socks used at Paris Saint-Germain last week, but as pointed out by Gary O’Hare and Jay, there was probably an issue with the ‘proper’ home socks, which have the same speckled effect as the shirt.
In any case, the change didn’t negatively affect them, as a 5-0 win illustrated.