Sky Sports sources understand Chelsea will make an improved bid for Tottenham's Luka Modric later on Monday.

Tottenham's resolve to be tested by improvement on initial £22m bid

Decisions

Gentleman's agreement

sources understand Chelsea will make an improved bid for wantaway Tottenham playmaker Luka Modric later on Monday. The Croatia international is at the centre of a transfer saga which is beginning to turn ugly, as claims and counter-claims are exchanged with Spurs chairman Daniel Levy. Chelsea failed in a £22million approach for Modric earlier in the summer, but last season's Premier League runners-up, now under the management of Andre Villas-Boas, are ready to increase their offer. The previous approach from Chelsea is believed to have determined the 25-year-old's thought process and on Monday morning it was revealed that he was prepared to request a transfer. Tottenham boss Harry Redknapp has dismissed reports that Modric has been forced to train by himself amid the squabble and claims he knows nothing of a new approach, but insists transfer decisions rest with Levy.Redknapp toldof Chelsea's interest: "If they are going to make an improved offer, I would think they need to. Twenty-two million pounds for Luka Modric would be a joke if he was for sale. "He is the most fantastic footballer, so the offer is a joke in terms of how much money they have offered and, most importantly of all, obviously we need to keep him." Redknapp added regarding the transfer stance over Modric: "At the end of the day, it is up to the chairman. The chairman makes those decisions. I certainly wouldn't want to lose him, but it is a difficult situation. "He is a fantastic boy, as I have said before, he is a great player. It is not easy when people come along and start offering you double, treble your wages. It must make it very difficult for him." Levy last week told a disenchanted Modric, a £16.6million signing from Dynamo Zagreb in 2008, that he will not be allowed to leave no matter what the size of the fee or the club making the approach.Modric has claimed this reneges on a gentleman's agreement he struck with Levy in May 2010, when he signed a six-year contract extension with Tottenham. It is contested by Modric that Spurs would listen to his thoughts if a perceivably bigger club showed an interest and made an appropriate offer. Chelsea, who, unlike Tottenham, will play in the UEFA Champions League in the forthcoming season, appear to meet this criteria in Modric's opinion. Spurs are of a different mind, but the impending increased bid, which is reported to be £27m, from their London rivals will tempt the resolve of Levy, who is likely to want at least £30m. Redknapp has previously admitted Modric has seemed distracted in pre-season training and reports have suggested Lyon's £9m-rated Bosnian, Miralem Pjanic, is being considered as a replacement.