The Primera Division leaders take on second-placed Atletico Madrid on Sunday, with Messi and Atletico's own hot-shot Radamel Falcao both likely to be on show at the Nou Camp.
Messi and Falcao have 39 league goals between them already this season with the former breaking Gerd Muller's all-time record for the number of goals in a calendar year, previously 85, in Barcelona's win at Real Betis last weekend.
Meanwhile Falcao, who missed training with a muscle injury on Thursday but is expected to play from the start on Sunday, smashed five goals in Atletico's 6-0 hammering of Deportivo on the same evening.
But it is the continuing goalscoring exploits of Messi, who has moved three ahead of Muller after netting twice against Betis and twice again in the cup win over Cordoba, which set him apart from the rest according to Mascherano.
"Messi is unique because he is already the best player in the history of this sport," Mascherano said.
"We are talking about 88 goals as if it were something normal but what he has done is incredible. This is a lad who has been touched by a magic wand."