The Iron Ones were trailing the home side with three-quarters of the game played before the Nigerian forward struck twice with assassin-like precision
Nigerian striker Taiwo Awoniyi grabbed a second-half brace to inspire Union Berlin to an excellent 2-1 win at Mainz on Sunday.
Despite firing blanks in his last three Bundesliga games, Awoniyi retained his starting spot at the MEWA ARENA in Mainz.
But he could only watch as Ingvartsen handed the hosts a deserved lead five minutes before the interval.
The 24-year-old had struck a fine effort in the 3-0 thrashing of Maccabi Haifa in the Europa League on Thursday, and he showed his high confidence level when he pounced on a Max Kruse pass to drag Union Berlin back on equalled terms in the 70th minute.
The former Liverpool man then put the Iron Ones in the lead for the first time in the match four minutes later, courtesy of a Behrens assist.
It's Awoniyi's second brace since his club-record move to Berlin in August. He equally netted twice when Urs Fischer's men humbled Finnish side KUPS 4-0 in the Conference League qualifier on August 19.
The Super Eagles hopeful now has five goals in seven Bundesliga games for Union, the same number of goals he hit in 21 matches while on loan at the club last term.
