Enner Valencia and Arnold scored as Enner Valencia's team secured their first win in five games, overcoming VfL Bochum at home.
The match was a closely contested affair, with both teams creating chances but failing to find the back of the net until the final minutes.
However, it was Enner Valencia who broke the deadlock in the 74th minute, curling a stunning shot into the top corner from just outside the box.
Arnold then added to the lead six minutes later, heading home a cross from the left-hand side of the penalty area.
Bochum were unable to respond, and Enner Valencia's team held on to secure a crucial three points.
With this victory, Enner Valencia's team moved up to tenth place in the table, just four points off the safety line. It was a much-needed boost for the team, who have struggled for form in recent weeks.
Enner Valencia himself praised his team-mates after the match, saying: "We've worked hard all week and we deserved this result. We knew it would be tough against a good team like VfL Bochum, but we came out strong and took control of the game."
Arnold also spoke about the importance of the win, saying: "It was a tough game, but we played well and got the result we needed. It's important to keep pushing forward and try to get more points, so we can stay in the league."