The £56 million striker grabbed his third goal for Arsenal since his arrival from Borussia Dortmund in January in the crucial 3-0 win over Watford on Sunday.
But the 29-year-old will now have to take a back seat on Thursday when Arsene Wenger’s side take on AC Milan in the second leg of their last 16 Europa league tie at the Emirates.
Aubameyang played for Dortmund in the group stages of the Champions League, but they dropped into the Europa League, and you cannot play for two cubs in the same competition under Uefa rules.
The striker hit Arsenal’s second goal against Watford, Shkodran Mustafi and Henrikh Mkhitaryan adding the others.
The Europa league is now Arsenal’s only chance of a trophy this season, and Aubameyang said: “I am really frustrated because of the rules.
“I am disappointed because I can’t help my team. That’s life. I have to deal with it.
“I can’t play every three days, and that is frustrating. When I was in Dortmund, I was playing every three days but now I play once a week or have a long time between games. It is not easy.”
The Gabon striker has struggled since his arrival at the Emirates, with some subdued performances as Arsenal as a team have battled to find any kind of form.
But successive goals in the league against Brighton and Watford will be a boost to his confidence, and he said: “It was a big win. The team did very well and it is a great three points. We needed it. I think the fans were happy, which is really important.
“It was a bit difficult for me at the beginning but I am feeling better now. I didn’t play a lot in January so it was difficult to find a rhythm.
“Now I am feeling better. I work hard, I have worked a lot in the last weeks and I am happy because I feel better.
“I am really happy for the boss because I am here because of him. He had the interest in me so I am happy to play for him.”
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