The in-form Chelsea winger scored in last-minute penalty in the reverse fixture against West Brom and notched a hat-trick in a 3-0 win over Newcastle last time out
Chelsea travels to the Hawthorns hoping to extend its lead at the top of the table to four points with Arsenal and Manchester City not in action until Wednesday - with the Baggies slipping into the relegation zone.
Mel is concerned by the threat posed by Hazard, who scored a controversial last-gasp penalty to deny West Brom victory at Stamford Bridge, rather than the man he locked horns with while in charge of Real Betis.
"Our problem is Chelsea. Our problem is Hazard. He scores goals, not Mourinho. We need concentration on the pitch. Ninety minutes for a good result," he told the Birmingham Mail. "My opinion is Jose Mourinho is a big manager and big coach. It's difficult to win in Portugal, Spain, England and Italy. He's a big coach.
"Does he talk too much? Sorry, but it's not my problem. My problem is Hazard, [Fernando] Torres, Willian, [Samuel] Eto'o. Mourinho is a good coach and manager and for me a good person. I watched the match in Spain and the last penalty was bad too. That is West Brom's life. But the best motivation for playing against Chelsea is Chelsea. They have good players and are a top team. That is the best motivation."
Mel also hinted that January signing Thievy Bifouma could make his first start for the club since joining on loan from Espanyol after he came off the bench to score in West Brom's 3-1 defeat at Crystal Palace.
"It is possible," he added. "The last match was good for him and it's possible he will be in the lineup. It is important for us because Chelsea are a consistent team and West Brom need a surprise."