The Scots - who drew with Lithuania on Saturday - fell behind when Robert Mak netted moments after the visitors felt Steven Fletcher was fouled in Trnava.

Mak sidestepped Russell Martin for the hosts' second before Adam Nemec rose unchallenged to head their third.

Scotland now sit fourth in Group F, three points behind leaders England.

Strachan's side - who have finished fourth in their last two qualifying campaigns - also trail Lithuania and Slovenia by a point while Slovakia's first win of the campaign means they have closed to within one of the Scots.

Scotland's next fixture is against England at Wembley on 11 November.

Strachan's big decisions

The starting line-up had a solid look to it once captain Darren Fletcher was passed fit to allow Strachan to combine him in central midfield with the hard-working James McArthur and the artful Barry Bannan.

But despite this trio of central midfielders, Scotland were often caught wide open by a limited Slovakia team.

Neither Celtic youngster Kieran Tierney - starting in place of Scotland's best player at the weekend, Andrew Robertson - nor Callum Paterson were offered enough support defensively from wide midfielders Robert Snodgrass and Matt Ritchie.

But it was the exclusion again of Leigh Griffiths that will garner most attention, the striker - who was lively when he came on - having scored more club goals than either the recalled Steven Fletcher or Griffiths' fellow substitute Chris Martin so far this season.

Strachan might reflect that Griffiths was his only seriously contentious decision but the reality is that his team did not deliver for him at a critical moment, making it questionable whether the campaign is now redeemable.

Defensive woes

Scotland have looked defensively vulnerable in all three games of their Group F World Cup qualifying campaign and that theme continued in Trnava, with Slovakia not having to work hard for their three goals.

There was no relentless pressure on the Scotland goal; instead Strachan's side were undone by a lack of defensive nous and organisation.

Mak was a handful throughout for under-fire central defenders Martin and Grant Hanley, but his goals were scored in isolation rather than following persistent probing by the home side.

When David Marshall pushed Marek Hamsik's header into the middle of the penalty area, Mak was unmarked as he lashed the ball into the net despite nine Scots being back to defend.

The forward's second came when he was granted too much time on the edge of the six-yard box and was able to shift the ball from one foot to the other, leaving Martin flailing helplessly, before slotting home coolly.

Nemec was then left unmarked at a corner for the third when again Scotland had plenty of defenders in attendance.

Strachan can justifiably point to the misfortune of Fletcher being fouled by Jan Durica before the first goal, but that incident occurred just outside Slovakia's penalty area with Scotland on the attack.

For the home side to be then taking the lead by sweeping up the pitch highlighted Scotland's disorderly set-up.

Scotland's missing cutting edge

Strachan's side showed they were capable of scoring goals in the last campaign and against Malta in September's 5-1 win, but failed to score against a poor Slovakia side.

While they were composed in possession at times, they found it hard to create clear chances.

Snodgrass was out of sorts - weakly shooting at Matus Kozacik with one of the best opportunities - and Matt Ritchie was reluctant to take on his full-back even when left one-on-one.

The overlapping of Tierney - Scotland's best player in the first half - created openings, but the wrong decisions were always taken with the crosses.

Fletcher awkwardly steered a header off target, as did McArthur, while Griffiths pulled a shot wide when he came on after the break.