Complex sentence: He made his professional debut 23 days later, coming on as a second-half substitute for Thomas Murg in a 0--3 away loss against SK Rapid Wien; he quickly became a regular starter, and appeared in 27 matches during the campaign.
Split into simpler sentences: He made his professional debut 23 days later, coming on as a second-half substitute for Thomas Murg in a 0--3 away loss against SK Rapid Wien. He quickly became a regular starter, and appeared in 27 matches during the campaign.