Definition of Travel Sickness

What is the meaning of the term 'travel sickness' in the game of football?

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There was a time when a team's dismal showing away from home was attributed to the long distances they had to commute, in other words 'travel sickness'. Over the years this term has evolved and become synonymous with mediocre or poor away performances for teams.

Manchester City manager Manuel Pellegrini was one who put great emphasis on curing 'travel sickness'. In 2013, midway through the EPL season when his club seemed to be floundering, he stressed the importance of winning away games. In fact, that became the key to City's success when they turned around by winning away-from-home fixtures consistently, especially important ones, and eventually going on to take the League title in 2014.