The line in the Hearts song that “the defence is as strong as the old castle rock” has rarely seemed more apt than it does at the moment.

Six clean sheets in their last seven games and only six goals against in that time means the Edinburgh club have the best defensive record in the league apart from Rangers, who visit Tynecastle on Sunday.

The fact they have shut out each of their last four visitors to Tynecastle means resurgent Hearts can welcome the league leaders to their manor with no shortage of confidence. Aside from Tottenham and St Johnstone, no side has scored more than one goal in a game against Hearts, while one of the goals was only shipped as a result of an unfortunate slip from goalkeeper Jamie MacDonald.

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Defensive solidity was paramount to the impressive run of last season chronicled on the opposite page and, with fit, foraging, full-backs, Jamie Hamill and Danny Grainger either side of the twin peaks, Marius Zaliukas and Andy Webster, there’s a feeling that plenty more shut-outs will be accrued in the coming weeks and months.

All the more so, given the support from combative midfielders such as Eggert Jonsson and Adrian Mrowiec, who are pretty handy themselves when called upon to deputise in defence.

“The last few games we’ve had a settled back four and, with Eggert and Adrian doing well in that defensive midfield role in front of them, we look really solid,” said Gary Locke, the Hearts first-team coach. “We got a bit of stick after the St Johnstone game and rightly so because we didn’t turn up, but, on the whole, we’ve looked really solid this season. If we can keep them all fit and they’re all playing regularly, then we’ll be a hard team to beat.”

Locke has been particularly impressed by Grainger and Hamill, who joined from St Johnstone and Kilmarnock respectively in the summer.

“The full-backs have done really well – for me Danny and Jamie have been the plus points of the season so far,” he continued. “When they come in from slightly smaller clubs, you’re always worrying about whether they’ll settle in, but the two of them have done brilliantly and are really enjoying their football just now.”

The burgeoning partnership between Webster and Zaliukas is also giving Locke plenty cause for optimism. “Webster and Zaliukas are as good as any other centre-back pairing in the league. The more they play together, the better they’ll get as a partnership, but certainly over the last two games they’ve looked formidable. People said when Andy first came back that him and Marius struggled a bit together but I didn’t see it that way at all. When you’ve got two top-class international defenders they’ll always find a way to play together. The big thing is keeping Andy fit, but he’s certainly looking sharper with every game. When he’s on song he’s a very good defender. If he can keep himself fit I’m certain he’ll force his way back into the Scotland squad.”

While Jim Jefferies’ team, featuring the likes of Ismael Bouzid and Lee Wallace in the back four, were a sturdy unit when they wanted to be, it’s safe to say the current manager also knows a thing or two about organising a backline. Indeed, all six of Hearts’ league clean sheets have come in the last eight games, since the Portuguese took charge.

Locke was keen to emphasise, however, that it’s not just the back four who merit credit for the fine stats Sergio is able to boast. “It’s down to the whole team, not just the back four, that we’ve been doing so well defensively. The back four look really steady but they’re definitely helped by having guys like Adrian, Eggert and Ian Black in front of them. All of those guys can put in a shift and make tackles and that all helps the defence.”

While Hearts defensive digits make for impressive reading, they are somewhat upstaged by Rangers. The Ibrox men have kept eight clean sheets in their 11 league games and haven’t conceded in any of their five away games.

“Rangers are the benchmark,” acknowledged Locke. “I’ve seen them a few times this season and they’re a quality side.”