Wales take on Scotland at Murrayfield on Saturday, needing victory to remain on course for this season's Guinness Six Nations title and a Grand Slam.
It will be their fourth Six Nations clean sweep if they see off Scotland and then defeat Ireland in Cardiff seven days later.
Here, Press Association Sport looks at Wales' performances in the fourth match of their three previous Six Nations Grand Slam campaigns – 2005, 2008 and 2012.
Scotland 22 Wales 46 (Murrayfield, March 13, 2005)
Wales moved closer to a first Five or Six Nations Grand Slam for 29 years after romping to a record win over Scotland in Edinburgh. A blistering first-half display saw them score 38 points as tries from Ryan Jones, Rhys Williams, Shane Williams and a Kevin Morgan double left the Scots in disarray. Although Scotland managed three touchdowns of their own during the second period, Wales had done more than enough, and they went on to beat Ireland six days later.
Wales: K Morgan; R Williams, T Shanklin, G Henson, S Williams; S Jones, D Peel; G Jenkins, M Davies, A Jones, B Cockbain, R Sidoli, R Jones (capt), M Williams, M Owen.
Ireland 12 Wales 16 (Croke Park, March 8, 2008)
Wales headed to Ireland's temporary Dublin home of Croke Park after winning the first three games of head coach Warren Gatland's reign, beating England at Twickenham, then Scotland and Italy in Cardiff. Ireland led 6-3 at half-time, but despite Wales having two players sin-binned, they prevailed through wing Shane Williams scoring a then Wales record-equalling 40th Test try and James Hook's late penalty. Wales won the Grand Slam through defeating France 29-12 the following weekend.
Wales: L Byrne; M Jones, T Shanklin, G Henson, S Williams; S Jones, M Phillips; G Jenkins, M Rees, A Jones, I Gough, A W Jones, J Thomas, M Williams, R Jones (capt).
Wales 24 Italy 3 (Millennium Stadium, March 10, 2012)
Italy arrived in Cardiff with Wales on a roll following victories over Ireland, Scotland and England, and while it proved to be a laboured home victory for Gatland's team, they got the job done. Leigh Halfpenny kicked three first-half penalties, and Wales eventually moved clear through tries by centre Jamie Roberts and wing Alex Cuthbert. The Grand Slam – a third in eight seasons – arrived when France were beaten 16-9 seven days later.
Wales: L Halfpenny; A Cuthbert, J Davies, J Roberts, G North; R Priestland, M Phillips; G Jenkins (capt), M Rees, A Jones, A W Jones, I Evans, D Lydiate, J Tipuric, T Faletau.