The 23-year old USA international became just the fourth American to reach the milestone of 20 goals in a European season when scoring in the 2-0 KNVB Beker (Dutch Cup) win over Roda JC on Tuesday night.
Johannsson added to Bart Biemans' first-half own-goal when firing home Viktor Elm's pass just before the hour-mark to tally his sixth goal of the tournament which helped put defending champions AZ through to the semi-finals.
Johannsson has scored 12 goals in 19 Eredivisie outings, netted in the Dutch Super Cup and tallied once in the Europa League qualifying stages to move to 20 goals in all competitions this term.
He joins Sunderland's Jozy Altidore (milestone achieved with AZ), Seattle Sounders' Clint Dempsey (with Fulham) and former US international Earnie Stewart (with Willem) as the Americans to get to 20 in one campaign in Europe.
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