Analysis - Tom English, BBC Scotland's chief sport writer

The grim confirmation of Sione Tuipulotu's Six Nations-ending injury was expected but it still landed with a thud nonetheless.

Tuipulotu is one of the form inside centres in the game; a captain, a physical brute, an artist, an inspiration to his team. He's a pretty rare amalgam of world-class bludgeon and world-class rapier.

His absence - and that of the outstanding lock Scott Cummings - has seen Scottish optimism, racing along merrily last week, reduced to a slow crawl. Glasgow have also suffered a double blow in the loss of two critical operators.

Tuipulotu's partnership with Huw Jones is a cosmic blend. Now an alternative is needed. Jones and his excellent Warriors' team-mate, Tom Jordan, don't pack enough physical punch for Test rugby as a duo. Franco Smith never plays them together at 12-13 for Glasgow.

The same could be said for Rory Hutchinson, the dangerous Northampton centre. A Hutchinson-Jones combo lacks enough muscle for the unforgiving fields of Six Nations rugby.

Most likely, it's going to be another Warriors pair, Stafford McDowall and Jones in the midfield in the championship.

McDowall is a tough operator and Glasgow's captain but nobody inside the Scotland camp is pretending Tuipulotu's absence is anything other than a nightmare.

As for Tuipulotu's fitness for the Lions - pretty much every pundit in all four nations has picked him at 12 in the Test series - let's just hope that his operation is successful and that his recovery is swift.

Losing Cummings is also hellish news given his power game and his form. Grant Gilchrist and Jonny Gray will surely now start against Italy in the opening day of the championship, but their back-up, Glasgow's Max Williamson, is also out for the tournament, so there are problems in multiple places.

Glasgow head coach Smith, like Gregor Townsend, must be a disappointed man today.

Scotland began their Six Nations season with two home games back-to-back, with Italy and then Ireland coming to Murrayfield in the first nine days of February.

The odds on Townsend's team causing a sensation this season will have drifted with Monday's news.