Tomorrow night, Chelsea host Tottenham Hotspur in the second leg of the Carabao Cup semi-final, seeking to overturn a first-leg deficit.
At Wembley a fortnight ago, Chelsea wore all-blue, having opted to use their yellow change kit in the Premier League in November.
According to commentator Martin Tyler, that switch was due to league regulations, but Tottenham were able to wear their default home kit away to both Leicester City and Cardiff City in December, with no problems.
While Tottenham have often worn white shorts at Stamford Bridge, they have engaged in this practice less in recent years, retaining the white shorts exclusively for European use. For an example of Chelsea changing shorts away to Spurs, you have to go back even further, to August 22, 1987.
While the Blues often wore white shorts with their home shirts during their Le Coq Sportif era, in both 1985-86 and 1986-87 Tottenham had an all-white home kit and so games at White Hart Lane saw Chelsea in all-blue.
However, Spurs’ new kit in the summer of 1987 saw the navy shorts restored and so, for the third game of the season, Chelsea took to the field in a set of white Umbro teamwear shorts with navy and grey panels on the right leg.
However, these were to prove to be a one-off, seemingly down to referee interpretation rather than a league-wide edict – as Chelsea expert Nik Yeomans points out, all-blue was worn that season away to Luton Town and Oxford United, both of whom had navy shorts.
Five seasons later, white replaced blue as the first-choice sock colour, recreating the classic 1960s and 1970s look, but the blue shorts have remained unchanged over the past three decades.