Bristol City manager Keith Millen says he is "concerned" by the lack of defensive options within his squad.
"We've lost two key defenders from last season and we've not replaced them yet," he told BBC Radio Bristol.
"And to conceed six goals in three games is not what we want so we are concerned about that."
He continued: "We are short on competition in the back four and that's something which has been ongoing this summer.
"It certainly doesn't help when you are mixing and matching the team but that's still no excuse."
Millen has struggled to bring in his defensive targets during the closed season, but is confident he will be able make the breakthrough by targetting top-flight players on short-term deals.
"We are constantly looking and watching games, we have got a list of players that we would like to bring in," he added.
"All you need is one positive phone call and we might have one in this week.
"We have got some options on some Premier League players that we are looking to loan, but at the moment they won't commit to anything.
"We're just trying to be patient, and if we get one or two in that will improve the squad."