Jose Mourinho has hinted that Chelsea may not increase their offer for Everton defender John Stones.
Everton have rejected a second Chelsea bid of £26 million for England defender Stones, 21, who made 23 Premier League starts last season.
"The market sometimes has no rules," Mourinho said. "We, as Chelsea, we make our own rules.
"To make our own rules is to evaluate the players, and to know the players' value, and to know when we have to stop and turn to another side and think in another option."
Mourinho has a strong squad but has said he is short of options in defence -- something he will seek to address before the transfer window closes.
Branislav Ivanovic, Kurt Zouma, Gary Cahill, Cesar Azpilicueta and John Terry are Chelsea's only first-team defenders.
"Five is not enough. That's obvious," Mourinho said. "We cannot go to the Premier League with five defenders. That's our weakness. The quality is good, but the numbers are not enough."
Information from the Press Association was used in this report.