Is it permissible to offer the Asr prayer before the Dhuhr prayer by combining them during travel?

Whoever intends to combine prayers (Jama' Ta'khir) must have the intention to do so before the time for the first prayer expires, with enough time to perform it. Otherwise, it will be considered a missed prayer (Qada'). In this case, one must hasten to perform the missed prayer before the current prayer, unless the time for the current prayer is running out, in which case one must begin with it. However, if one intends the combination during the time of the first prayer, then it is permissible to begin with the second prayer before the first.