Paul Merson predicts a difficult start to Southampton’s return to the Premier League against Newcastle United on Saturday. Russell Martin will be relishing the challenge of guiding Southampton into the Premier League in what will be his first taste of the division as a manager. Armed with eight first-team signings this summer, Martin will be putting the finishing touches on his Southampton side’s preparations to face Newcastle United at St James’ Park this weekend. It will be a baptism of fire in front of a raucous Newcastle home crowd that should go some way to revealing how effective Southam…