George Baldock scored his second goal of the season while helping Oxford United to four points over the two Christmas fixtures.
The win moved the U’s to second place in Sky Bet League 2 but they weren’t able to follow it up with another victory on Monday, as they were held to a goalless draw by Yeovil Town.
Baldock played the full 90 minutes for the 24th league game in succession, helping the Oxfordshire outfit keep their 12th clean sheet of 2015/16.
Tshimanga was handed the start by boss Kevin Wilson and played 70 minutes before being substituted with the score at 2-0.
Harwood’s spot-kick proved nothing more than a consolation in a 3-1 defeat but the Boro were able to respond on Monday with a 3-0 triumph at home to their rivals Tamworth.
Tshimanga came off the bench in the Boxing Day clash at Solihull Motors, winning a penalty which was converted by fellow striker Marlon Harewood.
Kabongo Tshimanga also featured in two games over the festive period, taking his appearance total for Nuneaton Town to seven.