By Tom Victor Xabi Alonso may regret his decision to stay at Bayer Leverkusen amid interest from Liverpool, according to former England star Paul Marson. Alonso, 42, is on course to win his first Bundesliga title with Leverkusen. The league leaders are 10 points clear with just eight matches remaining, and can still win the DFB-Pokal and Europa League after going the entire season unbeaten so far. Leverkusen’s form this season, as well as their climb up the Bundesliga table last term, have seen Alonso become hot property. His former clubs Liverpool and Bayern Munich have both been linked, with…