I fixed it!
I chanted the widget.php file in /leaguemanager/lib/
and changed the code lines 180-183 from
$out .= "<p class='match_day'>".sprintf(__("<strong>%d.</strong> Match Day", 'leaguemanager'), $match->match_day)."</p>";
$time = ( '00:00' == $match->hour.":".$match->minutes ) ? '' : mysql2date(get_option('time_format'), $match->date);
$out .= "<p class='date'>".mysql2date($instance['date_format'], $match->date).", <span class='time'>".$time."</span></p>";
to
$out .= "<p class='match_day'>".sprintf(__("<strong>Week %d</strong>", 'leaguemanager'), $match->match_day)."</p>";
$time = ( '00:00' == $match->hour.":".$match->minutes ) ? '' : mysql2date(get_option('time_format'), $match->date);
$out .= "<p class='date'>".mysql2date($instance['date_format'], $match->date)." <span class='time'>".$time."</span></p>";
and the code on line on 261 from
$out .= "<p class='match_day'>".sprintf(__("<strong>%d.</strong> Match Day", 'leaguemanager'), $match->match_day)."</p>";
to
$out .= "<p class='match_day'>".sprintf(__("<strong>Week %d</strong>", 'leaguemanager'), $match->match_day)."</p>";